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 A307974 Inverse binomial transform of the "original" Bernoulli numbers [A164555(n)/A027642(n)] with 1 and 1/2 swapped. Numerators. 1
 1, 1, -4, 2, -38, 3, -73, 4, -68, 5, -179, 6, -9218, 7, -19, 8, -3976, 9, 18143, 10, -89038, 11, 426463, 12, -118199108, 13, 4276511, 14, -11874736822, 15, 4307920527007, 16, -3854660524816, 17, 1288843929131, 18, -13157635776544491194, 19, 1464996956920721, 20, -130541359248224699708 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Denominators: 2, 2, 3, 1, 15, 1, 21, 1, 15, 1, 33, 1, ... . Denominators 3, 15, 21, 15, 33, 1365, 3, 255, ... coincide with cosecant numbers A001897, except 1 (conjectured). LINKS Table of n, a(n) for n=0..40. FORMULA a(2*n+1) = n+1 (conjectured). EXAMPLE Successive differences show the data in the first column: 1/2, 1, 1/6, 0, -1/30, 0, 1/42, 0, ... 1/2, -5/6, -1/6, -1/30, 1/30, 1/42, ... -4/3, 2/3, 2/15, 1/15, -1/105, ... 2, -8/15, -1/15, -8/105, ... -38/15, 7/15, -1/105, ... 3, -10/21, ... -73/21, ... ... . The third column is A256671(n)/A256675(n). MATHEMATICA m = 40; b[n_] = BernoulliB[n]; b[0] = 1/2; b[1] = 1; a[n_] := Sum[(-1)^(n - k)*Binomial[n, k]*b[k], {k, 0, m}] // Numerator; Table[a[n], {n, 0, m}] (* Second program: *) m = 40; bb = CoefficientList[Series[x/(1 - Exp[-x]), {x, 0, m}], x]*Range[0, m]!; bb[[1]] = 1/2; bb[[2]] = 1; a[n_] := Differences[bb, n][[1]] // Numerator; Table[a[n], {n, 0, m}] (* Jean-François Alcover, May 31 2019 *) CROSSREFS Cf. A001897, A027642, A164555, A176328 (for the second bisection), A256671/A256675, A306821 (denominators). Sequence in context: A364878 A102015 A302890 * A303625 A123850 A280780 Adjacent sequences: A307971 A307972 A307973 * A307975 A307976 A307977 KEYWORD sign,frac AUTHOR Paul Curtz, May 30 2019 STATUS approved

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Last modified July 19 12:08 EDT 2024. Contains 374394 sequences. (Running on oeis4.)