OFFSET
0,2
COMMENTS
Triangle is determined by rules 0) the top number is 1; 1) each number is the sum of the two below it; 2) it is left-right symmetric; 3) the numbers in each of the border rows, after the first 3, are alternately 0.
Up to signs this is the difference table of the Bernoulli numbers (see A212196). The Sage script below is based on L. Seidel's algorithm and does not make use of a library function for the Bernoulli numbers; in fact it generates the Bernoulli numbers on the fly. - Peter Luschny, May 04 2012
LINKS
Fabien Lange and Michel Grabisch, The interaction transform for functions on lattices Discrete Math. 309 (2009), no. 12, 4037-4048. [From N. J. A. Sloane, Nov 26 2011]
Peter Luschny, The computation and asymptotics of the Bernoulli numbers.
Ludwig Seidel, Über eine einfache Entstehungsweise der Bernoulli'schen Zahlen und einiger verwandten Reihen, Sitzungsberichte der mathematisch-physikalischen Classe der königlich bayerischen Akademie der Wissenschaften zu München, volume 7 (1877), 157-187. [Peter Luschny, May 04 2012]
FORMULA
T(n, 0) = (-1)^n*Bernoulli(n); T(n, k) = T(n-1, k-1) - T(n, k-1) for k=1..n. [Corrected (sign flipped) by R. J. Mathar, Jun 02 2010]
Let U(m, n) = (-1)^(m + n)*T(m+n, n). Then the e.g.f. for U(m, n) is (x - y)/(e^x - e^y). - Ira M. Gessel, Jun 12 2021
EXAMPLE
Triangle begins
1
1/2, 1/2
1/6, 1/3, 1/6
0, 1/6, 1/6, 0
-1/30, 1/30, 2/15, 1/30, -1/30
0, -1/30, 1/15, 1/15, -1/30, 0
1/42, -1/42, -1/105, 8/105, -1/105, -1/42, 1/42
0, 1/42, -1/21, 4/105, 4/105, -1/21, 1/42, 0
-1/30, 1/30, -1/105, -4/105, 8/105, -4/105, -1/105, 1/30, -1/30
MATHEMATICA
t[n_, 0] := (-1)^n BernoulliB[n];
t[n_, k_] := t[n, k] = t[n-1, k-1] - t[n, k-1];
Table[t[n, k] // Denominator, {n, 0, 10}, {k, 0, n}] (* Jean-François Alcover, Jun 04 2019 *)
PROG
(Sage) # uses[BernoulliDifferenceTable from A085737]
def A085738_list(n): return [q.denominator() for q in BernoulliDifferenceTable(n)]
A085738_list(6)
# Peter Luschny, May 04 2012
CROSSREFS
KEYWORD
AUTHOR
N. J. A. Sloane following a suggestion of J. H. Conway, Jul 23 2003
STATUS
approved