%I #11 Apr 15 2017 08:12:31
%S 37,59,67,101,103,131,149,233,257,263,271,283,293,307,311,347,389,401,
%T 409,421,433,461,463,523,541,557,577,593,607,613,619,653,659,677,683,
%U 727,751,757,761,773,797,811,821,827,839,877,881,887,953,971,1061,1091
%N Irregular primes (A000928) with irregularity index one.
%C A prime p is regular if and only if the numerators of the Bernoulli numbers B_2, B_4, ..., B_{p-3} (A000367) are not divisible by p.
%C In other words, irregular primes p dividing the numerator of B(2k) for a single k, 1<=k<(p-1)/2.
%H T. D. Noe, <a href="/A073276/b073276.txt">Table of n, a(n) for n=1..10000</a> (from Buhler et al.)
%H J. Buhler, R. Crandall, R. Ernvall, T. Metsankyla and M. A. Shokrollahi, <a href="http://dx.doi.org/10.1006/jsco.1999.1011">Irregular Primes and Cyclotomic Invariants to 12 Million</a>, J. Symbolic Computation 31, 2001, 89-96.
%H <a href="/index/Be#Bernoulli">Bernoulli numbers, irregularity index of primes</a>
%t 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 == 1, Print[p]], {n, 3, 200} ]
%Y Cf. A000928, A000367, A060974, A060975 and A073277.
%K nonn
%O 1,1
%A _Robert G. Wilson v_, Jul 22 2002