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 A231200 Boustrophedon transform of even numbers. 4
 0, 2, 8, 24, 72, 240, 924, 4116, 20944, 119952, 763540, 5346748, 40845816, 338041704, 3012855356, 28770647220, 293055401888, 3171602665696, 36343889387172, 439607533130732, 5597256953340360, 74829813397495128, 1048039052970587788, 15345654816688856484 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 0..400 Peter Luschny, An old operation on sequences: the Seidel transform J. Millar, N. J. A. Sloane and N. E. Young, A new operation on sequences: the Boustrophedon transform, J. Combin. Theory, 17A 44-54 1996 (Abstract, pdf, ps). Wikipedia, Boustrophedon_transform FORMULA a(n) = Sum_{k=0..n} A109449(n,k)*k*2. a(n) = 2*A231179(n). E.g.f.: 2*x*exp(x)*(sec(x) + tan(x)). - Ilya Gutkovskiy, Sep 27 2017 MATHEMATICA T[n_, k_] := SeriesCoefficient[(1+Sin[x])/Cos[x], {x, 0, n-k}] n!/k!; a[n_] := 2 Sum[k T[n, k], {k, 0, n}]; Table[a[n], {n, 0, 23}] (* Jean-François Alcover, Jun 28 2019 *) PROG (Haskell) a231200 n = sum \$ zipWith (*) (a109449_row n) \$ [0, 2 ..] CROSSREFS Cf. A005843, A000754. Sequence in context: A045697 A131569 A290904 * A066973 A130495 A026070 Adjacent sequences:  A231197 A231198 A231199 * A231201 A231202 A231203 KEYWORD nonn AUTHOR Reinhard Zumkeller, Nov 05 2013 STATUS approved

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Last modified June 20 10:03 EDT 2021. Contains 345162 sequences. (Running on oeis4.)