|
| |
|
|
A049479
|
|
Smallest prime dividing 2^n - 1.
|
|
9
| |
|
|
3, 7, 3, 31, 3, 127, 3, 7, 3, 23, 3, 8191, 3, 7, 3, 131071, 3, 524287, 3, 7, 3, 47, 3, 31, 3, 7, 3, 233, 3, 2147483647, 3, 7, 3, 31, 3, 223, 3, 7, 3, 13367, 3, 431, 3, 7, 3, 2351, 3, 127, 3, 7, 3, 6361, 3, 23, 3, 7, 3, 179951, 3, 2305843009213693951, 3, 7, 3, 31
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 2,1
|
|
|
LINKS
| T. D. Noe, Table of n, a(n) for n=2..500 (derived from Brillhart et al.)
Eric Weisstein's World of Mathematics, Mersenne Number
|
|
|
EXAMPLE
| a(6)=3 since 2^6 - 1 = 63 = 3^2*7
|
|
|
MATHEMATICA
| a = {}; Do[w = 2^n - 1; c = FactorInteger[w]; b = c[[1]][[1]]; AppendTo[a, b], {n, 2, 65}]; a - Artur Jasinski (grafix(AT)csl.pl), Dec 11 2007
|
|
|
CROSSREFS
| Cf. A005420.
Sequence in context: A186107 A019158 A086153 * A125314 A050393 A110778
Adjacent sequences: A049476 A049477 A049478 * A049480 A049481 A049482
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Olivier Gerard (olivier.gerard(AT)gmail.com)
|
|
|
EXTENSIONS
| More terms from Michael Lugo (mlugo(AT)thelabelguy.com), Dec 22 1999
|
| |
|
|
