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Search: id:A091887
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| A091887 |
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Irregularity index of the n-th irregular prime A000928(n). |
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+0
6
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| 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 1, 1, 2, 3, 1, 1, 2, 1, 1, 2, 1, 1, 1, 3, 1, 2, 3, 1, 1, 2, 1, 1, 2, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 1, 2, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 2, 1, 1, 1
(list; graph; listen)
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OFFSET
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1,8
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COMMENT
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See A091888 for definition.
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REFERENCES
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J. Buhler, R. Crandall, R. Ernvall, T. Metsankyla and M. A. Shokrollahi, Irregular Primes and Cyclotomic Invariants to 12 Million, J. Symbolic Computation 31, 2001, 89-96.
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..10000 (from Buhler et al)
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MATHEMATICA
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tp=Table[p=Prime[i]; cnt=0; k=1; While[2k<=p-3, If[Mod[Numerator[BernoulliB[2k]], p]==0, cnt++ ]; k++ ]; cnt, {i, 400}]; Select[tp, #>0&]
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CROSSREFS
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Cf. A073277 (primes having irregularity index 2), A060975 (primes having irregularity index 3), A061576 (least prime having irregularity index n), A091888 (irregularity index of prime(n)).
Sequence in context: A127937 A083911 A095827 this_sequence A144871 A066799 A037832
Adjacent sequences: A091884 A091885 A091886 this_sequence A091888 A091889 A091890
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KEYWORD
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nonn
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AUTHOR
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T. D. Noe (noe(AT)sspectra.com), Feb 09 2004
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