A000974 Conjecturally the number of even integers the sum of two primes in exactly n ways.

1, 4, 9, 11, 11, 16, 16, 18, 20, 23, 16, 29, 16, 25, 27, 23, 22, 25, 35, 29, 26, 25, 27, 27, 27, 33, 28, 44, 35, 21, 29, 35, 38, 33, 39, 37, 34, 35, 31, 31, 28, 41, 37, 32, 44, 35, 37, 41, 44, 33, 37, 32, 47, 39, 43, 47, 33, 37, 48, 41, 37, 48, 34, 35, 47, 36, 29, 36, 46, 44, 43, 38, 48

Offset

0,2

Links

T. D. Noe, Table of n, a(n) for n = 0..5000

Mathematica

f[n_] := Length[ Select[2n - Prime[ Range[ PrimePi[n]]], PrimeQ]]; a = Table[0, {75}]; Do[c = f[n]; If[c < 75, a[[c + 1]]++ ], {n, 5000}]; a (* Robert G. Wilson v, using Paul Abbott's coding in A002375, Apr 07 2005 *)

Crossrefs

Cf. A000954, A001172, A002375.

Sequence in context: A115675 A115668 A055675 * A291626 A376591 A312833

Adjacent sequences: A000971 A000972 A000973 * A000975 A000976 A000977

Keyword

nonn

Author

Bill Gosper

Status

approved