A062311 Number of ways writing n! as a sum of two primes.

0, 0, 0, 1, 3, 12, 39, 184, 951, 5531, 38713, 346207, 3130812, 34444964, 382437428, 4637235145

Offset: 0

Author

Labos Elemer, Jul 05 2001

Keywords

• nonn
• more

Comments

Number of unordered pairs of primes (p,q) such that n! = p + q.

Examples

			n = 4: 4! = 24 = 5+19 = 7+17 = 11+13 so a(4) = 3.
		

Crossrefs

Cf. A061358, A000142. See A140088 for a variant.

Formula

In other words, a(n) = A061358(n!) = number of prime+prime partitions of n!.

Extensions

a(9)-a(12) from Hans Havermann, Apr 29 2008

a(13) from Graeme McRae, May 02 2008

a(14)-a(15) from Hans Havermann, Dec 21 2008