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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..13.

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

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

Sequence in context: A175658 A191605 A277236 * A207095 A126358 A200051

Adjacent sequences:  A218205 A218206 A218207 * A218209 A218210 A218211

KEYWORD

nonn,base

AUTHOR

Martin Renner, Oct 23 2012

STATUS

approved

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Last modified December 3 20:56 EST 2020. Contains 338920 sequences. (Running on oeis4.)