A172366 Number of partitions of prime(n) into the sum of two semiprimes.

0, 0, 0, 0, 0, 1, 0, 2, 1, 2, 3, 2, 2, 4, 4, 3, 5, 6, 4, 6, 5, 5, 7, 4, 7, 6, 7, 7, 5, 5, 8, 8, 8, 8, 9, 10, 9, 7, 13, 10, 10, 11, 13, 10, 10, 10, 11, 15, 18, 13, 10, 13, 14, 16, 12, 18, 12, 15, 12, 11

Offset

1,8

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Formula

a(n) = A072931(A000040(n)).

Example

a(8)=2 because prime(8)=19=4(semiprime)+15(semiprime)=9(semiprime)+10(semiprime).

Mathematica

Table[Total[If[PrimeOmega[#]=={2, 2}, 1, 0]&/@Table[{x-n, n}, {n, x/2}]], {x, Prime[ Range[60]]}] (* Harvey P. Dale, Dec 21 2015 *)

Crossrefs

Cf. A129363, A175933,

Sequence in context: A320387 A304707 A112218 * A132148 A237829 A159974

Adjacent sequences: A172363 A172364 A172365 * A172367 A172368 A172369

Keyword

nonn

Author

Juri-Stepan Gerasimov, Nov 20 2010

Extensions

Corrected and extended by D. S. McNeil, Nov 20 2010

Status

approved