%I #9 Mar 24 2024 02:48:42

%S 1,3,5,15,13,5,25,63,41,13,61,15,85,25,14,255,145,41,181,23,25,61,265,

%T 95,313,85,365,27,421,14,481,1023,61,145,39,53,685,181,86,63,841,25,

%U 925,61,44,265,1105,383,1201,313,145,85,1405,365,63,95,181,421,1741,23,1861

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

%H Seiichi Manyama, <a href="/A111869/b111869.txt">Table of n, a(n) for n = 1..500</a>

%t f[n_] := Block[{k = 1, m = n^2}, While[ Mod[ Binomial[2k, k], m] != 0, k++ ]; k]; Array[f, 61]

%Y Cf. A000984, A059097, A073078.

%K nonn

%O 1,2

%A _Robert G. Wilson v_, Nov 23 2005