|
%I #9 Feb 18 2023 08:09:20
%S 0,0,6,12,0,12,0,24,18,15,0,60,0,0,60,48,0,36,0,60,42,0,0,168,0,0,54,
%T 84,0,120,0,96,66,0,210,180,0,0,78,360,0,105,0,132,180,0,0,336,0,75,
%U 102,156,0,108,66,168,114,0,0,660,0,0,504,192,0,132,0,204,138,420,0,504
%N Largest number k such that k*n/(k+n) and k*n/(k-n) are integers or 0 if no such number exists.
%H Antti Karttunen, <a href="/A243045/b243045.txt">Table of n, a(n) for n = 1..10080</a>
%e k*3/(k-3) and k*3/(k+3) are integers only for k=6. Thus since 6 is the largest k-value, a(3) = 6.
%o (PARI) a(n)=for(k=-n*(n+1),0,if(-k!=n,if((-k*n)/(-k+n)==0&&(-k*n)/(-k-n)==0,return(-k))))
%o n=1;while(n<100,print1(a(n),", ");n+=1)
%Y Cf. A243017, A243046, A243047 (positions of 0's), A360120 (their characteristic function).
%K nonn,look
%O 1,3
%A _Derek Orr_, May 29 2014
|
