%I #26 Aug 08 2014 14:46:36
%S 0,6,2,3,5,9,792,2555,10368,23464,84888,1047087,2483200,54721675,
%T 228537856,1394007616,5090444477,51286309703,608427634303,
%U 3260058995493,11314112766137,51848285189219,1034026438223449,11075640379838488,181108172062981288,1566869630866485093
%N Least number k >= 0 such that n! + k is a cube.
%H Robert Israel, <a href="/A240937/b240937.txt">Table of n, a(n) for n = 1..524</a>
%p f:= proc(n) local N; N:= n!; ceil(N^(1/3))^3 - N end proc:
%p seq(f(n), n=1..30); # _Robert Israel_, Aug 04 2014
%t f[n_] := Block[{c = n! - 1}, (1 + Floor[c^(1/3)])^3 - c - 1]; Array[f, 26] (* _Robert G. Wilson v_, Aug 04 2014 *)
%o (PARI)
%o a(n)=for(k=0,10^10,s=n!+k;if((ispower(s)&&ispower(s)%3==0)||s==1,return(k)))
%o n=1;while(n<20,print1(a(n),", ");n++)
%o (PARI) vector(50, n, ceil(n!^(1/3))^3-n!) \\ faster program
%Y Cf. A068869.
%K nonn
%O 1,2
%A _Derek Orr_, Aug 03 2014
%E a(15) onward from _Robert G. Wilson v_, Aug 04 2014
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