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 A168423 Triangle read by rows: expansion of (1 - x)/(exp(t)*(1 - x*exp(t*(1 - x)))) 0
 1, -1, 1, 1, -1, 1, -1, 1, 1, 1, 1, -1, 1, 7, 1, -1, 1, 1, 21, 21, 1, 1, -1, 1, 51, 161, 51, 1, -1, 1, 1, 113, 813, 813, 113, 1, 1, -1, 1, 239, 3361, 7631, 3361, 239, 1, -1, 1, 1, 493, 12421, 53833, 53833, 12421, 493, 1, 1, -1, 1, 1003, 42865, 320107, 607009, 320107, 42865 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,14 COMMENTS This sequence was derived from the Eulerian number umbral calculus expansion and A046802 by taking the exp(t) term and inverting it. What is interesting here is the '1,-1' terms that appear. I had thought I would get "1,5,1" not "1,7,1" from this function. An OEIS search came up with A046739 which has the same internal symmetric number structure. Inverse binomial transform of Eulerian numbers A123125. [Paul Barry, May 10 2011] LINKS FORMULA E.g.f. sum(T(n,k) t^n/n! x^k) = p(x,t) = (1 - x)/(exp(t)*(1 - x*exp(t*(1 - x)))) T(n,k)=sum{j=0..n, (-1)^(n-j)*C(n,j)*A123125(j,k)}. [Paul Barry, May 10 2011] EXAMPLE {1}, {-1, 1}, {1, -1, 1}, {-1, 1, 1, 1}, {1, -1, 1, 7, 1}, {-1, 1, 1, 21, 21, 1}, {1, -1, 1, 51, 161, 51, 1}, {-1, 1, 1, 113, 813, 813, 113, 1}, {1, -1, 1, 239, 3361, 7631, 3361, 239, 1}, {-1, 1, 1, 493, 12421, 53833, 53833, 12421, 493, 1}, {1, -1, 1, 1003, 42865, 320107, 607009, 320107, 42865, 1003, 1} MATHEMATICA p[t_] = (1 - x)/(Exp[t]*(1 - x*Exp[t*(1 - x)])) a = Table[ CoefficientList[FullSimplify[ExpandAll[n!*SeriesCoefficient[ Series[p[t], {t, 0, 30}], n]]], x], {n, 0, 10}]; Flatten[a] CROSSREFS Cf. A046802, A046739, A000166 (row sums), A123125. Sequence in context: A284097 A091258 A174544 * A336844 A072101 A088840 Adjacent sequences:  A168420 A168421 A168422 * A168424 A168425 A168426 KEYWORD sign,tabl AUTHOR Roger L. Bagula, Nov 25 2009 STATUS approved

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Last modified September 23 14:40 EDT 2021. Contains 347618 sequences. (Running on oeis4.)