OFFSET
1,3
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
a(5) = 6 because 5*6^2 + 1 = 181 is prime.
MATHEMATICA
Table[k = 0; While[!PrimeQ[n*k^2 + 1], k++]; k, {n, 110}]
PROG
(PARI) a(n) = my(k=1); while (!isprime(n*k^2 + 1), k++); k; \\ Michel Marcus, Aug 19 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Aug 05 2011
STATUS
approved