OFFSET
1,2
COMMENTS
FORMULA
A002972(a(n)) == 1 (mod 4), n >= 1.
EXAMPLE
MATHEMATICA
pmax = 2000; odd[p_] := Module[{k, m}, 2m+1 /. ToRules[Reduce[k>0 && m >= 0 && (2k)^2 + (2m+1)^2 == p, {k, m}, Integers]]]; Reap[For[n=1; p=5, p < pmax, p = NextPrime[p], If[Mod[p, 4]==1, If[Mod[odd[p], 4]==1, Sow[n]]; n++]]][[2, 1]] (* Jean-François Alcover, Feb 26 2016 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Wolfdieter Lang, Feb 06 2016
STATUS
approved