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A132184 Numbers n such that the numerator of the Bernoulli number B(2n) ends with the digits 691. +0
1
6, 21, 27, 321, 1266, 1527, 1821, 2526, 2576, 2721, 2950, 3126, 3246, 3426, 4206, 4236, 4821, 4926, 5286, 5721, 5946, 5950, 6100, 6351, 7018, 7138, 7172, 7386, 7806, 7931, 8037, 8790, 8796, 8826, 9021, 9048, 9426, 9478, 9726, 9921, 10221, 10326 (list; graph; listen)
OFFSET

1,1

COMMENT

The numerator of BernoulliB(12) is 691. The sequence gives a semi-indices of the 691-automorphic numerators in the BernoulliB(n) sequence. All 4 initial terms are the multiples of 3. Note that Bernoulli numerators corresponding to the first two terms are the automorphic primes: 691 and 1520097643918070802691.

LINKS

Eric Weisstein's World of Mathematics, Bernoulli Number.

EXAMPLE

a(1) = 6 because BernoulliB(2*6) = - 691/2730.

a(2) = 21 because BernoulliB(2*21) = 1520097643918070802691/1806.

a(3) = 27 because BernoulliB(2*27) = 29149963634884862421418123812691/798.

MATHEMATICA

Do[ g=Numerator[ BernoulliB[ 2n ] ]; f=Mod[ Abs[ g ], 1000 ]; If[ f==691, Print[ n ] ], {n, 1, 1000}]

CROSSREFS

Cf. A000367 = Numerators of Bernoulli numbers B_2n. Cf. A092132 = Indices n of Bernoulli numbers B(n) whose numerators are primes. Cf. A092133 = Prime numerators of Bernoulli numbers.

Sequence in context: A143416 A020880 A046467 this_sequence A143322 A034897 A064440

Adjacent sequences: A132181 A132182 A132183 this_sequence A132185 A132186 A132187

KEYWORD

base,nonn

AUTHOR

Alexander Adamchuk (alex(AT)kolmogorov.com), Nov 04 2007

EXTENSIONS

a(5)-a(42) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Sep 05 2008

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Last modified December 3 01:16 EST 2008. Contains 151161 sequences.


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