id:A111869 - OEIS Search Results

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Least number k such that C(2k,k) is divisible by n^2.

+0
2

1, 3, 5, 15, 13, 5, 25, 63, 41, 13, 61, 15, 85, 25, 14, 255, 145, 41, 181, 23, 25, 61, 265, 95, 313, 85, 365, 27, 421, 14, 481, 1023, 61, 145, 39, 53, 685, 181, 86, 63, 841, 25, 925, 61, 44, 265, 1105, 383, 1201, 313, 145, 85, 1405, 365, 63, 95, 181, 421, 1741, 23, 1861 (list; graph; listen)

	OFFSET	`1,2`
	MATHEMATICA	`f[n_] := Block[{k = 1, m = n^2}, While[ Mod[ Binomial[2k, k], m] != 0, k++ ]; k]; Array[f, 61]`
	CROSSREFS	`Cf. A059097.` `Sequence in context: A058220 A100181 A160046 this_sequence A093015 A066420 A102582` `Adjacent sequences: A111866 A111867 A111868 this_sequence A111870 A111871 A111872`
	KEYWORD	`nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Nov 23 2005`

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Last modified December 20 00:58 EST 2009. Contains 171054 sequences.

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