|
Search: id:A005420
|
|
|
| A005420 |
|
Largest prime factor of 2^n - 1.
(Formerly M2609)
|
|
+0
9
|
|
| 3, 7, 5, 31, 7, 127, 17, 73, 31, 89, 13, 8191, 127, 151, 257, 131071, 73, 524287, 41, 337, 683, 178481, 241, 1801, 8191, 262657, 127, 2089, 331, 2147483647, 65537, 599479, 131071, 122921, 109, 616318177, 524287, 121369, 61681, 164511353, 5419
(list; graph; listen)
|
|
|
OFFSET
|
2,1
|
|
|
REFERENCES
|
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
J. Brillhart et al., Factorizations of b^n +- 1. Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 2nd edition, 1985; and later supplements.
|
|
LINKS
|
T. D. Noe, Table of n, a(n) for n=2..500 (derived from Brillhart et al.)
J. Brillhart et al., Factorizations of b^n +- 1, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.
S. S. Wagstaff, Jr., The Cunningham Project
Eric Weisstein's World of Mathematics, Mersenne Number
|
|
EXAMPLE
|
2^6-1 = 63 = 3*21 = 9*7, so a(6) = 7.
|
|
PROGRAM
|
(PARI) for(n=2, 44, v=factor(2^n-1); print1(v[matsize(v)[1], 1], ", "))
|
|
CROSSREFS
|
Adjacent sequences: A005417 A005418 A005419 this_sequence A005421 A005422 A005423
Sequence in context: A112927 A064078 A048857 this_sequence A161818 A161509 A108974
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
N. J. A. Sloane (njas(AT)research.att.com).
|
|
EXTENSIONS
|
Description corrected by Michael Somos, Feb 24, 2002
More terms from Rick L. Shepherd (rshepherd2(AT)hotmail.com), Aug 22 2002
|
|
|
Search completed in 0.002 seconds
|
