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A205782
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Least positive integer k such that n divides C(k)-C(j) for some j in [1,k-1], where C=A205824.
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1
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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
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OFFSET
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1,1
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COMMENTS
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For a guide to related sequences, see A204892.
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LINKS
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EXAMPLE
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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
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MATHEMATICA
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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]}]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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