a(n) = 1 + 78557*2^n.

Terms

a(0) =157115a(1) =314229a(2) =628457a(3) =1256913a(4) =2513825a(5) =5027649a(6) =10055297a(7) =20110593a(8) =40221185a(9) =80442369a(10) =160884737a(11) =321769473a(12) =643538945a(13) =1287077889a(14) =2574155777a(15) =5148311553a(16) =10296623105a(17) =20593246209a(18) =41186492417a(19) =82372984833a(20) =164745969665a(21) =329491939329