OFFSET
0,1
COMMENTS
We consider the autosequence A164555(n)/A027642(n) (see A190339(n)) and its difference table without the first two rows and the first two columns:
2/15, 1/15, -1/105, -1/21, -1/105, 1/15, 7/165, -5/33,...
-1/15, -8/105, -4/105, 4/105, 8/105, -4/165, -32/165,...
-1/105, 4/105, 8/105, 4/105, -116/1155, -28/165,...
1/21, 4/105, -4/105, -32/231, -16/231,...
-1/105, -8/105, -116/1155, 16/231,...
-1/15, -4/165, 28/165,...
7/165, 32/165,...
5/33,... etc.
This is an autosequence of the second kind.
The antidiagonals are palindromes in absolute values.
a(n) are the denominators. Multiples of 3.
The sum of the even antidiagonals is A000004.
EXAMPLE
As a triangle:
15,
15, 15,
105, 105, 105,
21, 105, 105, 21,
105, 105, 105, 105, 105,
etc.
MATHEMATICA
max = 12; tb = Table[BernoulliB[n], {n, 0, max}]; td = Table[Differences[tb, n][[3 ;; -1]], {n, 2, max - 1}]; Table[td[[n - k + 1, k]] // Denominator, {n, 1, max - 3}, {k, 1, n}] // Flatten (* Jean-François Alcover, Apr 11 2014 *)
CROSSREFS
KEYWORD
AUTHOR
Paul Curtz, Mar 15 2014
STATUS
approved