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A125610
Smallest prime p such that 5^n divides p^4 - 1.
22
2, 7, 193, 443, 14557, 14557, 735443, 3124999, 7812499, 78124999, 292968749, 853235443, 2441406251, 53834264557, 122070312499, 202513391693, 1118040735443, 3459595983307, 3459595983307, 270488404577057
OFFSET
1,1
LINKS
MAPLE
f:= proc(n) local k, p2, P, t;
p2:= numtheory:-msqrt(-1, 5^n);
P:= sort([1, p2, 5^n-p2, 5^n-1]);
for k from 0 do
for t in P do
if isprime(k*5^n+t) then return k*5^n+t fi
od od:
end proc:
map(f, [$1..30]); # Robert Israel, Oct 27 2019
PROG
(PARI) See A125609 - Martin Fuller, Jan 11 2007
CROSSREFS
Cf. A125609 = Smallest prime p such that 3^n divides p^2 - 1. Cf. A125611 = Smallest prime p such that 7^n divides p^6 - 1. Cf. A125612 = Smallest prime p such that 11^n divides p^10 - 1. Cf. A125632 = Smallest prime p such that 13^n divides p^12 - 1. Cf. A125633 = Smallest prime p such that 17^n divides p^16 - 1. Cf. A125634 = Smallest prime p such that 19^n divides p^18 - 1. Cf. A125635 = Smallest prime p such that 257^n divides p^256 - 1.
Sequence in context: A042359 A015174 A307582 * A247028 A333740 A306951
KEYWORD
hard,nonn
AUTHOR
Alexander Adamchuk, Nov 28 2006
EXTENSIONS
More terms from Ryan Propper, Jan 02 2007
More terms from Martin Fuller, Jan 11 2007
STATUS
approved