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 A085738 Denominators in triangle formed from Bernoulli numbers. 14
 1, 2, 2, 6, 3, 6, 1, 6, 6, 1, 30, 30, 15, 30, 30, 1, 30, 15, 15, 30, 1, 42, 42, 105, 105, 105, 42, 42, 1, 42, 21, 105, 105, 21, 42, 1, 30, 30, 105, 105, 105, 105, 105, 30, 30, 1, 30, 15, 105, 105, 105, 105, 15, 30, 1, 66, 66, 165, 165, 1155, 231, 1155, 165, 165, 66, 66 (list; table; graph; refs; listen; history; text; internal format)
 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 REFERENCES 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. [From 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. 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] 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) # BernoulliDifferenceTable is defined in A085737. def A085738_list(n) : return map(denominator, BernoulliDifferenceTable(n)) A085738_list(6) # Peter Luschny, May 04 2012 CROSSREFS Cf. A085737, A212196. See A051714/A051715 for another triangle that generates the Bernoulli numbers. Sequence in context: A277021 A275037 A174833 * A227608 A276484 A100641 Adjacent sequences:  A085735 A085736 A085737 * A085739 A085740 A085741 KEYWORD nonn,frac,tabl AUTHOR N. J. A. Sloane following a suggestion of J. H. Conway, Jul 23 2003 STATUS approved

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Last modified August 23 00:50 EDT 2019. Contains 326211 sequences. (Running on oeis4.)