OFFSET
2,2
COMMENTS
EXAMPLE
For n = 4, 2^4 = 16 is the 9th composite number: 4,6,8,9,10,12,14,15,16, so a(4) = 9.
MATHEMATICA
Do[s=Mod[2^n, c[n]]; If[s==0, Print[n]], {n, 2, 1000000}]
Table[2^n-(PrimePi[2^n])-1, {n, 2, 31}]
PROG
(PARI) lista(kmax) = {my(c = 0); forcomposite(k = 1, kmax, c++; if(k >> valuation(k, 2) == 1, print1(c, ", "))); } \\ Amiram Eldar, Jun 04 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Nov 28 2001
EXTENSIONS
Edited by Robert G. Wilson v, Jun 18 2002
a(32)-a(34) from Amiram Eldar, Jun 04 2024
STATUS
approved