cp's OEIS Frontend

A205786 Least positive integer j such that n divides C(k)-C(j), where k, as in A205785, is the least number for which there is such a j, and C=A205825.

%I A205786 #9 Apr 12 2016 06:46:08
%S A205786 1,1,3,4,2,2,1,4,3,2,1,4,3,7,6,2,3,2,1,5,7,4,3,6,5,2,4,8,5,6,4,8,4,8,
%T A205786 7,4,5,5,3,6,12,7,3,6,6,6,3,8,7,5,8,2,3,4,7,8,3,5,2,6,6,4,9,8,6,4,7,8,
%U A205786 3,7,6,9,1,5,10,9,7,6,8,8,9,12,5,8,8,9,6,6,1,6,7,6,4,11,5,8,8
%N A205786 Least positive integer j such that n divides C(k)-C(j), where k, as in A205785, is the least number for which there is such a j, and C=A205825.
%C A205786 For a guide to related sequences, see A204892.
%e A205786 1 divides C(2)-C(1) -> k=2, j=1;
%e A205786 2 divides C(3)-C(1) -> k=3, j=1;
%e A205786 3 divides C(4)-C(3) -> k=4, j=3;
%e A205786 4 divides C(5)-C(4) -> k=5, j=4;
%e A205786 5 divides C(4)-C(2) -> k=4, j=2.
%t A205786 s = Table[n!/Ceiling[n/2]!, {n, 1, 120}];
%t A205786 lk = Table[
%t A205786   NestWhile[# + 1 &, 1,
%t A205786    Min[Table[Mod[s[[#]] - s[[j]], z], {j, 1, # - 1}]] =!= 0 &], {z, 1,
%t A205786     Length[s]}]
%t A205786 Table[NestWhile[# + 1 &, 1,
%t A205786   Mod[s[[lk[[j]]]] - s[[#]], j] =!= 0 &], {j, 1, Length[lk]}]
%t A205786 (* _Peter J. C. Moses_, Jan 27 2012 *)
%Y A205786 Cf. A204892, A205825.
%K A205786 nonn
%O A205786 1,3
%A A205786 _Clark Kimberling_, Feb 01 2012