a(n) is the smallest prime p such that 2^(p-1) == 1 (mod a(1)*...*a(n-1)*p).

Terms

a(0) =3a(1) =5a(2) =13a(3) =37a(4) =73a(5) =109a(6) =181a(7) =541a(8) =1621a(9) =4861a(10) =9721a(11) =19441a(12) =58321a(13) =87481a(14) =379081a(15) =408241a(16) =2041201a(17) =2449441a(18) =7348321a(19) =14696641a(20) =22044961a(21) =95528161a(22) =382112641a(23) =2292675841a(24) =8024365441a(25) =40121827201a(26) =481461926401a(27) =722192889601