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Numbers k such that (2*k)! * B(6*k) is an integer where B(k) are the Bernoulli numbers B(1)=-1/2 B(2)=1/6 B(4)=-1/30... B(2*m+1)=0 m>1.
1

%I #10 May 17 2021 04:09:43

%S 19,28,31,43,49,57,59,67,71,79,82,84,85,88,93,97,106,108,109,117,127,

%T 129,130,133,139,145,148,149,150,157,159,160,163,164,167,169,171,184,

%U 185,193,196,197,199

%N Numbers k such that (2*k)! * B(6*k) is an integer where B(k) are the Bernoulli numbers B(1)=-1/2 B(2)=1/6 B(4)=-1/30... B(2*m+1)=0 m>1.

%H Amiram Eldar, <a href="/A067777/b067777.txt">Table of n, a(n) for n = 1..10000</a>

%t Select[Range[200], IntegerQ[(2*#)! * BernoulliB[6*#]] &] (* _Amiram Eldar_, May 17 2021 *)

%Y Cf. A027641, A027642.

%K nonn

%O 1,1

%A _Benoit Cloitre_, Feb 06 2002