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A218207 Number of n-digit primes of the form (k-1)^2 + k^2. 4
1, 3, 6, 16, 42, 107, 286, 764, 2124, 5917, 17250, 49818, 145429 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

FORMULA

a(n) = A218208(n) - A218208(n-1)

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 *)

CROSSREFS

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

Sequence in context: A293949 A027088 A027102 * A019497 A091488 A202839

Adjacent sequences:  A218204 A218205 A218206 * A218208 A218209 A218210

KEYWORD

nonn,base

AUTHOR

Martin Renner, Oct 23 2012

STATUS

approved

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Last modified January 25 16:42 EST 2020. Contains 331245 sequences. (Running on oeis4.)