A126786 a(n) = n-th positive divisor of ((2n)!/n!^2).

1, 2, 4, 7, 6, 7, 11, 11, 20, 34, 17, 34, 25, 19, 19, 34, 27, 25, 25, 26, 33, 41, 36, 45, 47, 49, 98, 62, 40, 86, 88, 82, 57, 65, 67, 148, 142, 67, 92, 134, 61, 66, 56, 68, 71, 68, 63, 71, 83, 97, 106, 134, 77, 95, 166, 186, 222, 183, 113, 119, 103, 103, 107, 178, 134, 164

Offset: 1

Author

Leroy Quet, Feb 18 2007

Keywords

• nonn

Examples

			(2*5)!/5!^2 = 252. The divisors of 252 are 1, 2, 3, 4, 6, 7, 9, 12, 14, 18, 21, 28, 36, 42, 63, 84, 126, 252. The 5th of these is 6. So a(5) = 6.
		

Links

• David A. Corneth, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000984.

Programs

Mathematica

f[n_] := Divisors[(2n)!/n!^2][[n]];Array[f, 66] (* Ray Chandler, Feb 26 2007 *)

Extensions

Extended by Ray Chandler, Feb 26 2007

More terms from Emeric Deutsch, Feb 25 2007