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A205782 Least positive integer k such that n divides C(k)-C(j) for some j in [1,k-1], where C=A205824. 1
2, 3, 2, 4, 3, 3, 4, 5, 2, 3, 5, 5, 6, 4, 3, 6, 7, 3, 8, 4, 5, 5, 9, 6, 4, 6, 3, 4, 11, 3, 3, 7, 5, 7, 4, 5, 7, 8, 6, 6, 12, 5, 6, 5, 3, 9, 9, 6, 6, 4, 7, 6, 7, 3, 6, 5, 8, 11, 18, 6, 7, 10, 5, 7, 7, 5, 9, 7, 9, 4, 18, 6, 17, 7, 8, 8, 5, 6, 18, 7, 10, 12, 12, 5, 7, 6, 11, 6, 13, 3, 6, 9, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

For a guide to related sequences, see A204892.

LINKS

Table of n, a(n) for n=1..93.

EXAMPLE

1 divides C(2)-C(1) -> k=2, j=1

2 divides C(3)-C(2) -> k=3, j=2

3 divides C(2)-C(1) -> k=2, j=1

4 divides C(4)-C(3) -> k=4, j=3

5 divides C(3)-C(2) -> k=3, j=2

MATHEMATICA

s = Table[(3 n)!/(3 n*n!*(n + 1)!), {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, A205824.

Sequence in context: A238766 A286597 A246348 * A070296 A216647 A072645

Adjacent sequences:  A205779 A205780 A205781 * A205783 A205784 A205785

KEYWORD

nonn

AUTHOR

Clark Kimberling, Feb 01 2012

STATUS

approved

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Last modified February 17 20:03 EST 2018. Contains 299296 sequences. (Running on oeis4.)