A068905 - OEIS

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

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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 A081826 A021746

Adjacent sequences: A068902 A068903 A068904 * A068906 A068907 A068908

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Mar 06 2002

STATUS

approved