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%I #26 Apr 09 2013 14:55:58
%S 1,1,1,1,5,77,455,187,1616615,437437,8107385,607759061,53773464745,
%T 111446982977,2180460221945005,706769865044243,2275461421392965,
%U 3770118333635711057,19548063559901161830545,4094603218587147211,92990138354449826827902565
%N Quotients of (first) primorial numbers and denominators of Bernoulli numbers B 0, B 1, B 2, B 4, B 6,... .
%C a(2*n+4) is divisible by 5 (because A006954(n+2)=6,30,42,30,... is divisible by A165734(n)=period of length 2: repeat 6,30).
%F a(n) = A002110(n)/A006954(n).
%e a(0) = 1/1, a(1)= 2/2, a(2) = 6/6, a(3) = 30/30, a(4) =210/42=5.
%e By product (see A080092):
%e 1,
%e 1,
%e 1,
%e 1,
%e 5,
%e 7 * 11,
%e 5 * 7 *13,
%e 11 * 17,
%e 5 * 7 *11 *13 *17 *19,
%e 7 * 11 *13 *19 *23,
%e 5 * 11 *13 *17 *23 *29,
%e 7 * 13 *17 *19 *23 *29 *31,
%e 5 * 7 *11 *13 *17 *19 *29 *31 *37.
%t a[n_] := Product[ Prime[k], {k,1, n}] / Denominator[ BernoulliB[2*n-2] ]; a[0] = a[1] = 1; Table[a[n],{n,0,20}] (* _Jean-François Alcover_, Mar 15 2013 *)
%K nonn
%O 0,5
%A _Paul Curtz_, Mar 10 2013
%E More terms from _Jean-François Alcover_, Mar 15 2013
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