A218207 Number of n-digit primes of the form (k-1)^2 + k^2.

1, 3, 6, 16, 42, 107, 286, 764, 2124, 5917, 17250, 49818, 145429

Offset: 1

Author

Martin Renner, Oct 23 2012

Keywords

• nonn
• base

Crossrefs

Cf. A027861, A027862, A218208, A218209, A218211.

Programs

Mathematica

n = 0; Table[cnt = 0; 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) = A218208(n) - A218208(n-1)