A250305 - OEIS

A250305

a(0) = 1; a(n+1) is the smallest number not in the sequence such that a(n+1) - Sum_{i=1..n} a(i) divides a(n+1) + Sum_{i=1..n} a(i).

%I #9 Jan 25 2015 21:45:39

%S 1,2,4,5,6,9,18,15,20,40,60,90,135,243,216,288,384,512,1024,1536,2304,

%T 3456,5184,7776,11664,17496,26244,39366,59049,118098,98415,131220,

%U 174960,233280,311040,414720,552960,737280,983040,1310720,2621440,3932160,5898240,8847360

%N a(0) = 1; a(n+1) is the smallest number not in the sequence such that a(n+1) - Sum_{i=1..n} a(i) divides a(n+1) + Sum_{i=1..n} a(i).

%C If a(0) = 2, the sequence is the same; only a(0) and a(1) switch places.

%o (PARI) v=[1];print1(1,", ");n=1;while(n<10^4,if((V=vecsum(v))!=n&&(V+n)\(V-n)==(V+n)/(V-n)&&!vecsearch(vecsort(v),n),v=concat(v,n);print1(n,", ");n=0);n++)

%Y Cf. A250306.

%K nonn

%O 0,2

%A _Derek Orr_, Jan 15 2015