login
a(n) = binomial(sigma(n), n).
3

%I #15 Nov 04 2017 04:41:26

%S 1,3,4,35,6,924,8,6435,715,43758,12,30421755,14,1961256,1307504,

%T 300540195,18,62359143990,20,513791607420,129024480,3796297200,24,

%U 36052387482172425,736281,166509721602,12033222880,7648690600760440,30

%N a(n) = binomial(sigma(n), n).

%H Harry J. Smith, <a href="/A066090/b066090.txt">Table of n, a(n) for n=1..200</a>

%e a(4) = binomial(sigma(4),4) = binomial(7,4) = 7!/(4!3!) = 35.

%t Table[ Binomial[ DivisorSigma[1, n], n], {n, 1, 32} ]

%o (PARI) { for (n=1, 200, a=binomial(sigma(n), n); write("b066090.txt", n, " ", a) ) } \\ _Harry J. Smith_, Nov 12 2009

%Y Cf. A066449, A064366.

%K easy,nonn

%O 1,2

%A _Joseph L. Pe_, Dec 30 2001

%E Corrected and extended by _Robert G. Wilson v_, Dec 31 2001