A114648 - OEIS

A114648

Number of occurrences of 6 as a denominator in Bernoulli(k) for 0<=k<=10^n.

0, 1, 10, 87, 834, 7992, 77696, 758582, 7436825, 73129588, 720726912

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OFFSET

0,3

LINKS

Table of n, a(n) for n=0..10.

Eric Weisstein's World of Mathematics, Bernoulli Number

MATHEMATICA

DenominatorBernoulliBQ[n_Integer, denom_Integer] := If[EvenQ[n], Times @@ Select[Divisors[n] + 1, PrimeQ] == denom, 1 + KroneckerDelta[n, 1] == denom]; A114648[n_] := A114648[n] = Length[Select[Range[10^n], DenominatorBernoulliBQ[#, 6] &]] (* Enrique Pérez Herrero, Aug 01 2010 *)

CROSSREFS

Cf. A002445, A114649.

Cf. A051222, A045979. - Enrique Pérez Herrero, Aug 16 2010

Sequence in context: A331793 A121115 A292998 * A350134 A217417 A136864

Adjacent sequences: A114645 A114646 A114647 * A114649 A114650 A114651

KEYWORD

nonn,hard

AUTHOR

Eric W. Weisstein, Dec 21 2005

EXTENSIONS

More terms added by Enrique Pérez Herrero, Aug 01 2010

More terms from Enrique Pérez Herrero, Aug 16 2010

a(10) from Arkadiusz Wesolowski, Dec 02 2012

STATUS

approved