A066090 a(n) = binomial(sigma(n), n).
1, 3, 4, 35, 6, 924, 8, 6435, 715, 43758, 12, 30421755, 14, 1961256, 1307504, 300540195, 18, 62359143990, 20, 513791607420, 129024480, 3796297200, 24, 36052387482172425, 736281, 166509721602, 12033222880, 7648690600760440, 30
Offset: 1
Examples
a(4) = binomial(sigma(4),4) = binomial(7,4) = 7!/(4!3!) = 35.
Links
- Harry J. Smith, Table of n, a(n) for n=1..200
Programs
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Mathematica
Table[ Binomial[ DivisorSigma[1, n], n], {n, 1, 32} ] -
PARI
{ for (n=1, 200, a=binomial(sigma(n), n); write("b066090.txt", n, " ", a) ) } \\ Harry J. Smith, Nov 12 2009
Extensions
Corrected and extended by Robert G. Wilson v, Dec 31 2001