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URL: https://oeis.org/A218208

⇱ A218208 - OEIS

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A218208
Number of primes up to 10^n that are of the form (k-1)^2 + k^2.
4
1, 4, 10, 26, 68, 175, 461, 1225, 3349, 9266, 26516, 76334, 221763
OFFSET
1,2
FORMULA
a(n) = sum(A218207(k), k=1..n)
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 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Martin Renner, Oct 23 2012
STATUS
approved