OFFSET
1,1
COMMENTS
It is conjectured that the sequence of primes of the form k^2+1 is infinite, but this has never been proved. This sequence contains a subset of squares: {64, 144, 100, 1024, 4900, 10816, 11664, 12544, 18496, 102400, 41616, ...}.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
a(2) = 12 because (4^2+1)-(2^2+1) = 17 - 5 = 12.
MATHEMATICA
Differences[Select[Range[250]^2 + 1, PrimeQ]]
PROG
(PARI) lista(nn) = my(v=select(x->issquare(x-1), primes(nn))); vector(#v-1, k, v[k+1] - v[k]) \\ Michel Marcus, Dec 04 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Jul 30 2011
STATUS
approved