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A000734 Boustrophedon transform of 1,1,2,4,8,16,32,... 5

%I

%S 1,2,5,15,49,177,715,3255,16689,95777,609875,4270695,32624329,

%T 269995377,2406363835,22979029335,234062319969,2533147494977,

%U 29027730898595,351112918079175,4470508510495609,59766296291090577

%N Boustrophedon transform of 1,1,2,4,8,16,32,...

%C Binomial transform of A062272. - _Paul Barry_, Jan 21 2005

%H Reinhard Zumkeller, <a href="/A000734/b000734.txt">Table of n, a(n) for n = 0..400</a>

%H Peter Luschny, <a href="http://oeis.org/wiki/User:Peter_Luschny/SeidelTransform">An old operation on sequences: the Seidel transform</a>

%H 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 (<a href="http://neilsloane.com/doc/bous.txt">Abstract</a>, <a href="http://neilsloane.com/doc/bous.pdf">pdf</a>, <a href="http://neilsloane.com/doc/bous.ps">ps</a>).

%H N. J. A. Sloane, <a href="/transforms.txt">Transforms</a>

%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Boustrophedon_transform">Boustrophedon transform</a>

%H <a href="/index/Bo#boustrophedon">Index entries for sequences related to boustrophedon transform</a>

%F E.g.f.: (1+exp(2x))(sec(x)+tan(x))/2. - _Paul Barry_, Jan 21 2005

%F a(n) ~ n! * (1+exp(Pi)) * (2/Pi)^(n+1). - _Vaclav Kotesovec_, Oct 07 2013

%t CoefficientList[Series[(1+E^(2*x))*(Sec[x]+Tan[x])/2, {x, 0, 20}], x]* Range[0, 20]! (* _Vaclav Kotesovec_, Oct 07 2013 *)

%t t[n_, 0] := If[n == 0, 1, 2^(n-1)]; 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-Fran├žois Alcover_, Feb 12 2016 *)

%o (Sage) # Algorithm of L. Seidel (1877)

%o def A000734_list(n) :

%o A = {-1:0, 0:1}; R = []

%o k = 0; e = 1; Bm = 1

%o for i in range(n) :

%o Am = Bm

%o A[k + e] = 0

%o e = -e

%o for j in (0..i) :

%o Am += A[k]

%o A[k] = Am

%o k += e

%o Bm += Bm

%o R.append(A[e*i//2]/2)

%o return R

%o A000734_list(22) # _Peter Luschny_, Jun 02 2012

%o (Haskell)

%o a000734 n = sum $ zipWith (*) (a109449_row n) (1 : a000079_list)

%o -- _Reinhard Zumkeller_, Nov 04 2013

%Y Cf. A109449, A000079, A000752.

%K nonn

%O 0,2

%A _N. J. A. Sloane_, _Simon Plouffe_

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Last modified March 30 19:49 EDT 2020. Contains 333127 sequences. (Running on oeis4.)