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 A000697 Boustrophedon transform of 1, 1, 4, 9, 16, ... 4
 1, 2, 7, 26, 89, 316, 1243, 5564, 28321, 162160, 1032051, 7226636, 55206161, 456886912, 4072080587, 38885496092, 396084390849, 4286637591872, 49121248360291, 594159600856332, 7565074996215025, 101137602761945440 (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 on transform, J. Combin. Theory, 17A 44-54 1996 (Abstract, pdf, ps). N. J. A. Sloane, Transforms Wikipedia, Boustrophedon transform FORMULA E.g.f.: ( 1 + exp(x)*x*(1+x) )*(sec(x)+tan(x)). - Sergei N. Gladkovskii, Oct 29 2014 a(n) ~ n! * (4 + exp(Pi/2)*Pi*(2+Pi)) * 2^n / Pi^(n+1). - Vaclav Kotesovec, Jun 12 2015 MATHEMATICA t[n_, 0] := If[n==0, 1, n^2]; t[n_, k_] := t[n, k] = t[n, k-1]+t[n-1, n-k]; a[n_] := t[n, n]; Array[a, 30, 0] (* Jean-François Alcover, Feb 12 2016 *) PROG (Haskell) a000697 n = sum \$ zipWith (*) (a109449_row n) (1 : tail a000290_list) -- Reinhard Zumkeller, Nov 04 2013 CROSSREFS Cf. A109449, A000290, A000745. Sequence in context: A220304 A300451 A212961 * A027417 A134063 A087448 Adjacent sequences:  A000694 A000695 A000696 * A000698 A000699 A000700 KEYWORD nonn AUTHOR STATUS approved

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Last modified September 29 21:59 EDT 2020. Contains 337432 sequences. (Running on oeis4.)