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A073277
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Irregular primes with irregularity index two.
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7
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157, 353, 379, 467, 547, 587, 631, 673, 691, 809, 929, 1291, 1297, 1307, 1663, 1669, 1733, 1789, 1933, 1997, 2003, 2087, 2273, 2309, 2371, 2383, 2423, 2441, 2591, 2671, 2789, 2909, 2957, 3391, 3407, 3511, 3517, 3533, 3539, 3559, 3593, 3617, 3637, 3851
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Subsequence of A060974.
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REFERENCES
| 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
| T. D. Noe, Table of n, a(n) for n=1..10000 (from Buhler et al)
Bernoulli numbers, irregularity index of primes
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MATHEMATICA
| Do[p = Prime[n]; k = 1; c = 0; While[ 2*k < p - 3, If[ Mod[ Numerator[ BernoulliB[2*k]], p] == 0, c++ ]; k++ ]; If[ c == 2, Print[p]], {n, 3, 550} ]
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CROSSREFS
| Cf. A000928, A091887, A000367, A060974, A060975 and A073276.
Sequence in context: A140625 A142874 A060974 * A180233 A096708 A142833
Adjacent sequences: A073274 A073275 A073276 * A073278 A073279 A073280
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KEYWORD
| nonn
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AUTHOR
| Robert G. Wilson v (rgwv(AT)rgwv.com), Jul 22 2002
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