OFFSET
1,1
COMMENTS
Indices of terms in A056927 that are not prime.
LINKS
Richard L. Francis, Between consecutive squares, Missouri Journal of Mathematical Sciences, Volume 16 Issue #1 - Winter 2004.
EXAMPLE
a(1) = 2, since 2^2 - 3 = 1.
a(2) = 11, since 11^2 - 113 = 8.
a(3) = 17, since 17^2 - 283 = 6.
a(4) = 23, since 23^2 - 523 = 6.
MATHEMATICA
f[n_] := n^2 - NextPrime[n^2, -1]; Select[Range[2, 230], !PrimeQ[f[#]] &]
PROG
(PARI) lista(nn) = for (n=2, nn, if (!isprime(n^2-precprime(n^2)), print1(n, ", "))); \\ Michel Marcus, Mar 22 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Carlos Eduardo Olivieri, Mar 17 2015
STATUS
approved