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%I #6 Dec 04 2016 19:46:26
%S 2,3,2,3,2,4,4,3,5,3,6,4,3,8,2,3,4,9,10,3,5,12,12,4,4,5,6,8,5,4,16,5,
%T 7,5,4,9,6,20,5,3,5,10,22,12,6,24,24,4,14,7,4,5,7,9,7,8,11,7,30,4,6,
%U 32,8,6,3,14,34,5,13,8,36,9,8,7,7,20,9,5,40,3,6,9,42,10,4,44,5
%N Least positive integer k such that n divides k^4-j^4 for some j in [1,k-1].
%C For a guide to related sequences, see A204892.
%e 1 divides 2^4-1^4 -> k=2, j=1
%e 2 divides 3^4-1^4 -> k=3, j=1
%e 3 divides 2^4-1^4 -> k=2, j=1
%e 4 divides 3^4-1^4 -> k=3, j=1
%e 5 divides 2^4-1^4 -> k=2, j=1
%e 6 divides 4^4-2^4 -> k=4, j=2
%t s = Table[n^4, {n, 1, 120}] ;
%t lk = Table[
%t NestWhile[# + 1 &, 1,
%t Min[Table[Mod[s[[#]] - s[[j]], z], {j, 1, # - 1}]] =!= 0 &], {z, 1,
%t Length[s]}]
%t Table[NestWhile[# + 1 &, 1,
%t Mod[s[[lk[[j]]]] - s[[#]], j] =!= 0 &], {j, 1, Length[lk]}]
%t (* _Peter J. C. Moses_, Jan 27 2012 *)
%Y Cf. A204892.
%K nonn
%O 1,1
%A _Clark Kimberling_, Feb 01 2012
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