A136030 Smallest prime factor of composite Mersenne numbers.

23, 47, 233, 223, 13367, 431, 2351, 6361, 179951, 193707721, 228479, 439, 2687, 167, 11447, 7432339208719, 2550183799, 745988807, 3391, 263, 32032215596496435569, 5625767248687, 86656268566282183151, 18121, 852133201, 150287, 2349023, 730753, 359, 43441, 383

Offset

1,1

Links

Max Alekseyev, Table of n, a(n) for n = 1..188

Mathematica

a = {}; Do[If[PrimeQ[n] && !PrimeQ[2^n - 1], w = 2^n - 1; c = FactorInteger[w]; b = c[[1]][[1]]; AppendTo[a, b]], {n, 2, 130}]; a

Prog

(PARI) lista() = {vi = readvec("c:/gp/bfiles/b054723.txt"); vm = vector(#vi, i, 2^vi[i]-1); for (i=1, #vm, print1(factor(vm[i])[1, 1], ", "); ); } \\ Michel Marcus, May 14 2014

Crossrefs

Cf. A049479, A016047.

Sequence in context: A065017 A140618 A042052 * A054693 A180945 A052229

Adjacent sequences: A136027 A136028 A136029 * A136031 A136032 A136033

Keyword

nonn

Author

Artur Jasinski, Dec 11 2007

Extensions

More terms from Michel Marcus, May 14 2014

Terms to a(150) in b-file from Charles R Greathouse IV, May 14 2014

a(151)-a(188) in b-file added at the suggestion of Eric Chen by Max Alekseyev, Apr 25 2022

Status

approved