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A068904 a(n) = binomial(sigma(n),tau(n)), where sigma(n) is the sum and tau(n) the number of divisors of n (A000203, A000005). 4

%I #30 Feb 24 2024 01:02:33

%S 1,3,6,35,15,495,28,1365,286,3060,66,376740,91,10626,10626,169911,153,

%T 3262623,190,5245786,35960,58905,276,2558620845,4495,111930,91390,

%U 32468436,435,11969016345,496,67945521,194580,316251,194580,783768050065,703,487635

%N a(n) = binomial(sigma(n),tau(n)), where sigma(n) is the sum and tau(n) the number of divisors of n (A000203, A000005).

%H Alois P. Heinz, <a href="/A068904/b068904.txt">Table of n, a(n) for n = 1..10000</a> (first 1024 terms from Antti Karttunen)

%t Table[Binomial[DivisorSigma[1, n], DivisorSigma[0, n]], {n, 50}] (* _Carl Najafi_, Oct 10 2011 *)

%o (PARI) a(n)=binomial(sigma(n),numdiv(n)) \\ _Charles R Greathouse IV_, Feb 19 2013

%Y Cf. A068905, A068903, A204292.

%K nonn

%O 1,2

%A _Reinhard Zumkeller_, Mar 06 2002

%E More terms from _Carl Najafi_, Oct 10 2011

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Last modified April 19 23:15 EDT 2024. Contains 371798 sequences. (Running on oeis4.)