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| Abo Installasjon AS | Blommenholm | 1997 |
| Abo Maskin AS | Oppstryn | 1997 |
| Abobaha Maling & Fliser AS | Kleppe | 2022 |
| Abora Prosjekt AS | Arnatveit | 2000 |
| Abot AS | Barkåker | 2015 |
| Abp Elektro AS | Færvik | 2012 |
| Abp Elektro Holding AS | Færvik | 2012 |
| Abraham Invest AS | Oslo | 2020 |
| Abraham Mul | Fr-06540 Breil Sur Roya | 2019 |
| Abrahams Hus AS | Trondheim | 2016 |
| Abrahamsen Bygg Og Vedlikehold AS | Lyngdal | 2012 |
| Abrahamsen Bygningsvern Ltd Nuf | Enebakk | 2024 |
| Abrahamsen Gulvbehandling AS | Skien | 2025 |
| Abrahamsen Holding AS | Tønsberg | 2005 |
| Abrahamsen Service & Malerfirma AS | Kristiansand S | 2024 |
| Abrahamsson & Haugstvedt AS | Krokstadelva | 2001 |
| Abrs Rør Sætre AS | Sætre | 2012 |
| Abryn Holding AS | Degernes | 2024 |
| Abs Entreprenør AS | Fåvang | 2020 |
| Abs Fredrikstad AS | Rolvsøy | 2012 |
| Abs Sicherheitstechnik Vertriebs- Und Service GmbH | De-55129 Mainz | 2017 |
| Abs Sicherungstechnik GmbH & Co. KG | De-55129 Mainz | 2026 |
| Abs-Teknikk AS | Jonsvatnet | 2025 |
| Absoflex AB | Halden | 2001 |
| Absolutt Anlegg AS | Samuelsberg | 2023 |
| Absolutt Betongsaging AS | Frogner | 2017 |
| Absolutt Bygg. AS | Bodø | 2021 |
| Absolutt Byggservice AS | Kongsvinger | 2012 |
| Absolutt Maskin AS | Frogner | 2025 |
| Absystems No Nuf | Lv-3016 Kalnciems Jelgavas Novads | 2016 |
| Abt Alstahaug Byggteknikk AS | Sandnessjøen | 2020 |
| Abtek International | Dk-6270 Tønder | 2025 |
| Abu Montasje AS | Fjerdingby | 2021 |
| Abundantia Holding AS | Florvåg | 2025 |
| Abus Entreprenør AS | Kjøllefjord | 2001 |
| Abvei AS | Hardbakke | 2017 |
| Abygger AS | Namsos | 2024 |
| Ac Elektro AS | Paradis | 2023 |
| Ac Klima AS | Skedsmokorset | 2014 |
| Ac Service AS | Alta | 2022 |
| Ac Teknikk AS | Klepp Stasjon | 2026 |
| Ac Varmepumper AS | Oslo | 2007 |
| Ac Vestfold AS | Tønsberg | 2021 |
| Ac/Dc Marine Consult AS | Bergen | 2012 |
| Academica Malerentreprenøren AS | Lørenskog | 2006 |
| Academica Måleri Skåne | Se-24543 Helsingborg | 2014 |
| Acc Tromsø AS | Tromsø | 2015 |
| Accent Dariusz Wysocki | 83-047 Przywidz | 2006 |
| Accept Elektro Og Automasjon AS | Billingstad | 2000 |
| Access 24/7 AS | Sandnessjøen | 2008 |
| Acciona Construccion S.A. Nuf | Oslo | 2015 |
| Acciona Infraestructuras and Ghella Ans | Oslo | 2015 |
| Accumuli Security Limited | Basingstoke Rg21 4Af | 2015 |
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| Acdc Holding AS | Nesoddtangen | 2024 |
| Ace Eknes AS | Holmsbu | 2021 |
| Ace Elektro AS | Skien | 2020 |
| Acebi Service | 44150 Saint-Herblon | 2010 |
| Acel Baltic Uab | Ålesund | 2005 |
| Aceta AS | Tiller | 2013 |
| Acg Byggservice AS | Laksevåg | 2018 |
| Aco Anlegg AS | Tennfjord | 2010 |
| Aco Møre Holding AS | Tennfjord | 2024 |
| Aco Transport AS | Tennfjord | 2008 |
| Acom Elektro AS | Stavanger | 2018 |
| Acorp Construction AS | Oslo | 2020 |
| Acorp Holding AS | Oslo | 2009 |
| Acp Solutions AS | Ågotnes | 2025 |
| ACR elektro AS | Jar | 1986 |
| Acro Bygg AS | Oslo | 2004 |
| Acrylicon Baltic Uab | Lt-03113 Vilnius | 2010 |
| Acrylicon Industrigulv AS | Sande I Vestfold | 2005 |
| Acrylicon Midt- Og Vest- Norge AS | Flatåsen | 1994 |
| Acrylicon Nord-Norge AS | Bodø | 1994 |
| Acrylicon Rogaland AS | Aksdal | 2003 |
| Acs Elektroautomasjon AS | Klepp Stasjon | 2020 |
| Acsea Invest AS | Klepp Stasjon | 2020 |
| Acsent.As AS | Bergen | 2026 |
| Acsenteret Trondheim AS | Malvik | 2010 |
| Act M&B AB | Se-593 62 Västervik | 2018 |
| Acta AS | Holmestrand | 2020 |
| Actavo Norge AS | Oslo | 2021 |
| Acterna Nuf | Ee-51013 Tartu | 2023 |
| Activa Prosjekt AS | Tvedestrand | 2016 |
| Active Elektro AS | Sandnes | 2014 |
| Acu-Elektro Nuf | Fi-68500 Kronoby | 2026 |
| Acusto AS | Kristiansand S | 1987 |
| Acutus AS | Gressvik | 2020 |
| Ad Bygg & VVS AS | Blomsterdalen | 2015 |
| Ad Constructions AS | Blomsterdalen | 2021 |
| Ad Flisdesign AS | Andebu | 2025 |
| Ad Malerarbeid AS | Aurskog | 2009 |
| Ad Norwik AS | Drammen | 2025 |
| Ad Oppussing AS | Oslo | 2016 |
| Ad Probygg AS | Flatåsen | 2020 |
| Ad Rør AS | Auli | 2025 |
| Ad-Group AS | Arendal | 1999 |
| Ad-Speed Nuf | Pl- 36-220 Jasienica Rosielna | 2017 |
| Ada Bygg AS | Drøbak | 2026 |