cp's OEIS Frontend

A051907 Number of ways to express 1 as the sum of distinct unit fractions such that the sum of the denominators is n.

%I A051907 #13 May 29 2018 08:09:00
%S A051907 1,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,1,1,1,0,0,
%T A051907 0,0,1,1,0,0,0,0,1,0,2,0,0,0,0,2,0,1,1,1,1,0,2,0,1,1,1,2,0,4,1,3,4,0,
%U A051907 2,0,6,0,1,2,1,3,0,4,2,1,5,5,3,2,3,3,5,5,5,2,1,12,5,4,11,4,5,2,11,3,5
%N A051907 Number of ways to express 1 as the sum of distinct unit fractions such that the sum of the denominators is n.
%H A051907 Seiichi Manyama, <a href="/A051907/b051907.txt">Table of n, a(n) for n = 1..150</a>
%H A051907 <a href="/index/Ed#Egypt">Index entries for sequences related to Egyptian fractions</a>
%e A051907 1 = 1/2+1/4+1/9+1/12+1/18 = 1/2+1/5+1/6+1/12+1/20. The sum of the denominators of each of these is 45, these are the only 2 with sum of denominators = 45, so a(45)=2.
%Y A051907 A051882 lists n such that a(n)=0.
%Y A051907 Cf. A051908.
%K A051907 nonn
%O A051907 1,45
%A A051907 _Jud McCranie_, Dec 16 1999
%E A051907 R. L. Graham showed that a(n)>0 for n>77.