Since Fallout 1+2 soundtracks are used in New Vegas they can be found in MP3 format in the [Steam Versions]'s game files. : r/Fallout
Fallout 4 - Main Theme - Piano Version - Intermediate Level By Inon Zur - Digital Sheet Music For Score - Download & Print A0.936659 | Sheet Music Plus
Free sheet music: Fallout 4 - Main Theme [Full]- by Inon Zur, Play and Download any time
Theme From Fallout 4 By - Digital Sheet Music For Piano Solo - Download & Print HX.369223 | Sheet Music Plus
Inon Zur - Fallout 4 Main Theme MP3 Download & Lyrics | Boomplay