

A178813


(Prime(n)^(p1)  1)/p^2 mod p, where p is the first prime that divides (prime(n)^(p1)  1)/p.


2



487, 4, 1, 1, 46, 1, 0, 1, 11, 1, 2, 1, 0, 2
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OFFSET

1,1


COMMENTS

(Prime(n)^(p1)  1)/p^2 mod p, where p = A174422(n) is the first Wieferich prime base prime(n).
(Prime(n)^(p1)  1)/p^2 mod p, where p is the first prime such that p^2 divides prime(n)^(p1)  1.
See references and additional comments, links, and crossrefs in A001220 and A039951.


LINKS

Table of n, a(n) for n=1..14.
Wikipedia, Generalized Wieferich primes


FORMULA

a(n) = k mod 2, if prime(n) = 4k+1.
a(n) = A178814(prime(n)) .
a(1) = A178812(1).


EXAMPLE

Prime(2) = 3 and the first prime p that divides (3^(p1)  1)/p is 11, so a(2) = (3^10  1)/11^2 mod 11 = 488 mod 11 = 4.


CROSSREFS

Cf. A001220, A039951, A174422, A178812, A178814.
Sequence in context: A097765 A179428 A252076 * A178814 A178812 A124667
Adjacent sequences: A178810 A178811 A178812 * A178814 A178815 A178816


KEYWORD

hard,more,nonn


AUTHOR

Jonathan Sondow, Jun 17 2010


STATUS

approved



