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A060975 Irregular primes with irregularity index three. 11
491, 617, 647, 1151, 1217, 1811, 1847, 2939, 3833, 4003, 4657, 4951, 6763, 7687, 8831, 9011, 10463, 10589, 12073, 13217, 14533, 14737, 14957, 15287, 15787, 15823, 16007, 17681, 17863, 18713, 18869, 20533, 20939, 24019, 24659, 25153, 26561 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

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.

LINKS

T. D. Noe, Table of n, a(n) for n=1..9824 (from Buhler et al)

Bernoulli numbers, irregularity index of primes

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 == 3, Print[p]], {n, 3, 1000} ]

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 == 3, Print@p], {n, 3, 13887} ]

CROSSREFS

Cf. A000928, A000367, A060974, A060975, A073276 and A073277.

Sequence in context: A056936 A056052 A051115 * A180457 A082079 A217118

Adjacent sequences:  A060972 A060973 A060974 * A060976 A060977 A060978

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Jul 22 2002, extended Sep 20 2006

STATUS

approved

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Last modified October 24 20:44 EDT 2014. Contains 248516 sequences.