A168426 Square array of denominators of a truncated array of Bernoulli twin numbers (A168516), read by antidiagonals.

3, 6, 6, 30, 15, 30, 30, 15, 15, 30, 42, 105, 105, 105, 42, 42, 21, 105, 105, 21, 42, 30, 105, 105, 105, 105, 105, 30, 30, 15, 105, 105, 105, 105, 15, 30, 66, 165, 165, 1155, 231, 1155, 165, 165, 66, 66, 33, 165, 165, 231, 231, 165, 165, 33, 66, 2730, 15015, 15015, 15015, 15015, 15015, 15015, 15015

Offset

0,1

Comments

Entries are multiples of 3.

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

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

Links

Table of n, a(n) for n=0..62.

Mathematica

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 *)

Crossrefs

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

Sequence in context: A223048 A319446 A181372 * A065931 A137497 A032338

Adjacent sequences: A168423 A168424 A168425 * A168427 A168428 A168429

Keyword

nonn,tabl,frac

Author

Paul Curtz, Nov 25 2009

Extensions

More terms from R. J. Mathar, Jul 10 2011

Status

approved