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A205794 Least positive integer j such that n divides C(k)-C(j) , where k, as in A205793, is the least number for which there is such a j, and C=A002808 (composite numbers). 0
1, 1, 2, 1, 1, 1, 3, 1, 2, 1, 1, 1, 3, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 1, 3, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 3, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 3, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 3, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 3, 1, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Is this sequence bounded?  For a guide to related sequences, see A204892.

LINKS

Table of n, a(n) for n=1..99.

EXAMPLE

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

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

3 divides C(4)-C(2) -> k=4, j=2

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

5 divides C(4)-C(1) -> k=4, j=1

6 divides C(5)-C(1) -> k=5, j=1

MATHEMATICA

s = Select[Range[2, 120], ! PrimeQ[#] &]

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.

Sequence in context: A111604 A101491 A276949 * A241665 A175307 A324825

Adjacent sequences:  A205791 A205792 A205793 * A205795 A205796 A205797

KEYWORD

nonn

AUTHOR

Clark Kimberling, Feb 01 2012

STATUS

approved

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Last modified December 14 19:27 EST 2019. Contains 329987 sequences. (Running on oeis4.)