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URL: https://oeis.org/A087522

⇱ A087522 - OEIS

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A087522
a(0) = 2; for n>=1, a(n) = smallest prime p such that p+1 is divisible by an n-th power > 1.
15
2, 2, 3, 7, 31, 31, 127, 127, 1279, 3583, 5119, 6143, 8191, 8191, 81919, 131071, 131071, 131071, 524287, 524287, 14680063, 14680063, 109051903, 109051903, 654311423, 738197503, 738197503, 2147483647, 2147483647, 2147483647, 2147483647
OFFSET
0,1
COMMENTS
Trivially the n-th power under consideration is 2^n for n > 1.
LINKS
John Mason, using Robert Israel's data for A127582, Table of n, a(n) for n = 0..3310
FORMULA
a(n) << 37^n by Xylouris' improvement to Linnik's theorem. - Charles R Greathouse IV, Dec 10 2013
EXAMPLE
a(1) = 2 because 3^1|3.
a(2) = 3 because 2^2|4.
a(3) = 7 because 2^3|8.
PROG
(PARI) okdivs(pp1, n) = fordiv(pp1, d, if ((d>1) && ispower(d, n), return (1))); 0
a(n) = {if (n == 0, return (2)); p = 2; while (! okdivs(p+1, n), p = nextprime(p+1)); return (p); } \\ Michel Marcus, Sep 14 2013
CROSSREFS
A127582 is identical except for a(1).
Sequence in context: A077001 A180996 A307503 * A092970 A052449 A053413
KEYWORD
nonn
AUTHOR
Amarnath Murthy, Sep 11 2003
EXTENSIONS
More terms from Ray Chandler, Sep 14 2003
Edited by N. J. A. Sloane, Jul 03 2008
STATUS
approved