OFFSET
1,2
LINKS
Eric Weisstein's World of Mathematics, Thabit ibn Kurrah's rules
FORMULA
a(n) = A002235(n) + 1. - Jinyuan Wang, Jan 30 2020
EXAMPLE
3*2^(3-1) - 1 = 11 so a(1) = 3.
MATHEMATICA
Do[If[PrimeQ[3*2^(n - 1) - 1], Print[n]], {n, 1, 8000}] (* Mohammed Bouayoun (Mohammed.Bouayoun(AT)yahoo.fr), Apr 13 2006 *)
PROG
(PARI) for (i=1, 1000, if(isprime(3*2^(i-1)-1), print1(i, ", ")))
CROSSREFS
KEYWORD
nonn
AUTHOR
Mohammed Bouayoun (bouyao(AT)wanadoo.fr), Mar 17 2004
EXTENSIONS
More terms from Mohammed Bouayoun (Mohammed.Bouayoun(AT)yahoo.fr), Apr 13 2006
More terms from Jinyuan Wang, Jan 30 2020
STATUS
approved