A218208 Number of primes up to 10^n that are of the form (k-1)^2 + k^2.

1, 4, 10, 26, 68, 175, 461, 1225, 3349, 9266, 26516, 76334, 221763

Offset: 1

Author

Martin Renner, Oct 23 2012

Keywords

• nonn
• base

Crossrefs

Cf. A027861, A027862, A218207, A218210, A218212.

Programs

Mathematica

n = 0; cnt = 0; Table[While[n++; p = 2*n^2 - 2*n + 1; p < 10^e, If[PrimeQ[p], cnt++]]; n--; cnt, {e, 10}] (* T. D. Noe, Oct 23 2012 *)

Formula

a(n) = sum(A218207(k), k=1..n)