A195132 - OEIS

A195132

Least k such that k*666^n-1 is prime.

3, 5, 4, 3, 12, 44, 37, 7, 2, 7, 27, 80, 14, 32, 12, 14, 53, 32, 3, 87, 62, 13, 32, 13, 237, 147, 35, 63, 48, 35, 32, 44, 34, 32, 18, 28, 17, 12, 130, 250, 47, 108, 112, 73, 25, 5, 149, 44, 14, 129, 208, 238, 10, 13, 212, 124, 37, 180, 80, 212, 4, 19, 124, 42, 17, 112, 47, 27, 214, 84, 95, 182, 73, 957, 59, 68, 47, 13, 199, 130, 194, 75, 24

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..83.

C. Caldwell and P. Kaiser, 139·666^178851 - 1, Sep 08 2011

EXAMPLE

a(1)=3 since 3*666 is the least multiple of 666^1 such that k*666^1-1 is prime.

a(178851) <= 139 since 139*666^178851-1 is prime (cf. link).

PROG

(PARI) a(n)={ n=666^n; for(k=1, 1e9, ispseudoprime(k*n-1)&return(k)) }

for(e=1, 199, for(k=1, 1e9, ispseudoprime(k*666^e-1)&!print1(k", ")&break))