A068905 Binomial(sigma(n),omega(n)), where sigma(n) is the sum of divisors of n (A000203) and omega the number of distinct prime factors (A001221).

1, 3, 4, 7, 6, 66, 8, 15, 13, 153, 12, 378, 14, 276, 276, 31, 18, 741, 20, 861, 496, 630, 24, 1770, 31, 861, 40, 1540, 30, 59640, 32, 63, 1128, 1431, 1128, 4095, 38, 1770, 1540, 4005, 42, 142880, 44, 3486, 3003, 2556, 48, 7626

Offset

1,2

Links

G. C. Greubel, Table of n, a(n) for n = 1..1000

Mathematica

Binomial[DivisorSigma[1, #], Length[FactorInteger[#]]]&/@Range[50]  (* Harvey P. Dale, Feb 18 2011 *)

Prog

(PARI) a(n)=binomial(sigma(n), omega(n)) \\ Charles R Greathouse IV, Feb 19 2013

Crossrefs

Cf. A068903, A068904.

Sequence in context: A334127 A095001 A344458 * A241625 A021746 A081826

Adjacent sequences: A068902 A068903 A068904 * A068906 A068907 A068908

Keyword

nonn

Author

Reinhard Zumkeller, Mar 06 2002

Status

approved