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Square array of denominators of a truncated array of Bernoulli twin numbers (A168516), read by antidiagonals.
5

%I #19 Dec 21 2016 12:06:25

%S 3,6,6,30,15,30,30,15,15,30,42,105,105,105,42,42,21,105,105,21,42,30,

%T 105,105,105,105,105,30,30,15,105,105,105,105,15,30,66,165,165,1155,

%U 231,1155,165,165,66,66,33,165,165,231,231,165,165,33,66,2730,15015,15015,15015,15015,15015,15015,15015

%N Square array of denominators of a truncated array of Bernoulli twin numbers (A168516), read by antidiagonals.

%C Entries are multiples of 3.

%C The sequence of fractions A051716()/A051717() is a sequence of first differences of A164555()/A027642().

%C It can be observed (see the difference array in A190339) that A168516/A168426 is a sequence of autosequences of the second kind. - _Paul Curtz_, Dec 21 2016

%t max = 11; c[0] = 1; c[n_?EvenQ] := BernoulliB[n] + BernoulliB[n-1]; c[n_?OddQ] := -BernoulliB[n] - BernoulliB[n-1]; cc = Table[c[n], {n, 0, max+1}]; diff = Drop[#, 2]& /@ Table[ Differences[cc, n], {n, 0, max-1}]; Flatten[ Table[ diff[[n-k+1, k]], {n, 1, max}, {k, 1, n}]] // Denominator (* _Jean-François Alcover_, Aug 09 2012 *)

%Y Cf. A085738, A085737, A168516, A190339, A240581/A239315.

%K nonn,tabl,frac

%O 0,1

%A _Paul Curtz_, Nov 25 2009

%E More terms from _R. J. Mathar_, Jul 10 2011