|
| |
|
|
A086258
|
|
a(n) is the smallest k such that 2^k+1 has n primitive prime factors.
|
|
1
| |
|
|
0, 14, 26, 46, 83, 118, 309, 194, 414, 538, 786
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
COMMENTS
| A prime factor of 2^n+1 is called primitive if it does not divide 2^r+1 for any r<n. See A086257 for the number of primitive prime factors in 2^n+1. It is known that a(8) = 194.
Next term is > 666. - David Wasserman (wasserma(AT)spawar.navy.mil), Feb 25 2005
|
|
|
REFERENCES
| J. Brillhart et al., Factorizations of b^n +- 1. Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.
|
|
|
LINKS
| J. Brillhart et al., Factorizations of b^n +- 1 Available on-line
|
|
|
EXAMPLE
| a(2) = 14 because 2^14+1 = 5*29*113 and 29 and 113 do not divide 2^r+1 for r < 14.
|
|
|
CROSSREFS
| Cf. A086257.
Cf. A086252.
Sequence in context: A082773 A112772 A155505 * A063799 A086451 A190991
Adjacent sequences: A086255 A086256 A086257 * A086259 A086260 A086261
|
|
|
KEYWORD
| hard,more,nonn
|
|
|
AUTHOR
| T. D. Noe (noe(AT)sspectra.com), Jul 14 2003
|
|
|
EXTENSIONS
| More terms from David Wasserman (wasserma(AT)spawar.navy.mil), Feb 25 2005
a(11) from D. S. McNeil (mcneil(AT)hku.hk), Dec 19 2010
|
| |
|
|
