This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A219742 #31 Feb 16 2025 08:33:18
%S A219742 30,42,66,138,282,354,498,642,1002,1074,1362,1434,1578,2082,2154,2298,
%T A219742 2658,2802,2874,3018,3378,3522,3882,3954,4314,4962,5034,5178,5322,
%U A219742 5898,6114,7122,7338,7554,7698,7842,7914,8202,8634,8922,8994,9138,9714,10722
%N A219742 Bernoulli denominators with 8 divisors in increasing order (without repetitions).
%C A219742 Let m, n >= 1 and let f(m) denote number of Bernoulli numbers less than or equal to 10^m having denominator divisible by a(n). For any n, f(m) = floor(10^m/(a(n)/6 - 1)). It appears that the fraction of even Bernoulli numbers with denominator 6 is not so close to 1/6.
%H A219742 Arkadiusz Wesolowski, <a href="/A219742/b219742.txt">Table of n, a(n) for n = 1..10000</a>
%H A219742 Paul Erdős and Samuel S. Wagstaff, Jr., <a href="http://www.renyi.hu/~p_erdos/1980-45.pdf">The fractional parts of the Bernoulli numbers</a>, Illinois J. Math. 24 (1980), pp. 104-112.
%H A219742 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/BernoulliNumber.html">Bernoulli Number</a>
%H A219742 <a href="/index/Be#Bernoulli">Index entries for sequences related to Bernoulli numbers</a>
%F A219742 a(n) = 6*A092307(n).
%F A219742 A002445 INTERSECT A138636.
%t A219742 6*Prime@Flatten@Position[Table[p = Prime[n]; Length@Select[Divisors[p - 1] + 1, PrimeQ], {n, 277}], 3]
%Y A219742 Cf. A002445, A092307, A114648, A138636.
%K A219742 nonn
%O A219742 1,1
%A A219742 _Arkadiusz Wesolowski_, Nov 29 2012