cp's OEIS Frontend

A137791 Number of ways to write n as sum of two positive numbers having no prime gaps in their factorization.

%I A137791 #4 Mar 30 2012 18:50:59
%S A137791 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,
%T A137791 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,
%U A137791 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
%N A137791 Number of ways to write n as sum of two positive numbers having no prime gaps in their factorization.
%H A137791 R. Zumkeller, <a href="/A137791/b137791.txt">Table of n, a(n) for n = 1..10000</a>
%e A137791 a(20) = #{1+19,2+18,3+17,4+16,5+15,7+13,8+12,9+11} = 8;
%e A137791 a(21) = #{2+19,3+18,4+17,5+16,6+15,8+13,9+12} = 7;
%e A137791 a(22) = #{3+19,4+18,5+17,6+16,7+15,9+13,11+11} = 7;
%e A137791 a(23) = #{4+19,5+18,6+17,7+16,8+15,11+12} = 6;
%e A137791 a(24) = #{1+23,5+19,6+18,7+17,8+16,9+15,11+13,12+12} = 8.
%Y A137791 Cf. A073491, A002375, A061358, A071330, A137792, A137793.
%K A137791 nonn
%O A137791 1,4
%A A137791 _Reinhard Zumkeller_, Feb 11 2008