A137791 - OEIS

A137791

Number of ways to write n as sum of two positive numbers having no prime gaps in their factorization.

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

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

OFFSET

1,4

LINKS

R. Zumkeller, Table of n, a(n) for n = 1..10000

EXAMPLE

a(20) = #{1+19,2+18,3+17,4+16,5+15,7+13,8+12,9+11} = 8;

a(21) = #{2+19,3+18,4+17,5+16,6+15,8+13,9+12} = 7;

a(22) = #{3+19,4+18,5+17,6+16,7+15,9+13,11+11} = 7;

a(23) = #{4+19,5+18,6+17,7+16,8+15,11+12} = 6;

a(24) = #{1+23,5+19,6+18,7+17,8+16,9+15,11+13,12+12} = 8.

CROSSREFS

Cf. A073491, A002375, A061358, A071330, A137792, A137793.

Sequence in context: A368086 A167232 A319468 * A351834 A096125 A140828

Adjacent sequences: A137788 A137789 A137790 * A137792 A137793 A137794

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Feb 11 2008

STATUS

approved

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