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A085738
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Denominators in triangle formed from Bernoulli numbers.
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14
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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
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OFFSET
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0,2
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COMMENTS
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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
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LINKS
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FORMULA
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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
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EXAMPLE
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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
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MATHEMATICA
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t[n_, 0] := (-1)^n BernoulliB[n];
t[n_, k_] := t[n, k] = t[n-1, k-1] - t[n, k-1];
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PROG
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(Sage) # uses[BernoulliDifferenceTable from A085737]
def A085738_list(n): return [q.denominator() for q in BernoulliDifferenceTable(n)]
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CROSSREFS
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See A051714/A051715 for another triangle that generates the Bernoulli numbers.
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KEYWORD
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AUTHOR
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STATUS
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approved
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