

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.


1



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, 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, 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
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OFFSET

1,3


COMMENTS

For a guide to related sequences, see A204892.


LINKS

Table of n, a(n) for n=1..97.


EXAMPLE

1 divides C(2)C(1) > k=2, j=1;
2 divides C(3)C(1) > k=3, j=1;
3 divides C(4)C(3) > k=4, j=3;
4 divides C(5)C(4) > k=5, j=4;
5 divides C(4)C(2) > k=4, j=2.


MATHEMATICA

s = Table[n!/Ceiling[n/2]!, {n, 1, 120}];
lk = Table[
NestWhile[# + 1 &, 1,
Min[Table[Mod[s[[#]]  s[[j]], z], {j, 1, #  1}]] =!= 0 &], {z, 1,
Length[s]}]
Table[NestWhile[# + 1 &, 1,
Mod[s[[lk[[j]]]]  s[[#]], j] =!= 0 &], {j, 1, Length[lk]}]
(* Peter J. C. Moses, Jan 27 2012 *)


CROSSREFS

Cf. A204892, A205825.
Sequence in context: A096411 A228340 A227004 * A213812 A143486 A257820
Adjacent sequences: A205783 A205784 A205785 * A205787 A205788 A205789


KEYWORD

nonn


AUTHOR

Clark Kimberling, Feb 01 2012


STATUS

approved



