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 A208355 Right edge of the triangle in A208101. 6
 1, 1, 1, 2, 2, 5, 5, 14, 14, 42, 42, 132, 132, 429, 429, 1430, 1430, 4862, 4862, 16796, 16796, 58786, 58786, 208012, 208012, 742900, 742900, 2674440, 2674440, 9694845, 9694845, 35357670, 35357670, 129644790, 129644790, 477638700, 477638700, 1767263190 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 0..1000 D. Levin, L. Pudwell, M. Riehl, A. Sandberg, Pattern Avoidance on k-ary Heaps, Slides of Talk, 2014. FORMULA a(n) = A000108(floor((n+1)/2)), where A000108 = Catalan numbers. a(n) = A208101(n,n). a(n) = abs(A099363(n)). Conjecture: -(n+3)*(n-2)*a(n) -4*a(n-1) +4*(n-1)^2*a(n-2)=0. - R. J. Mathar, Aug 04 2015 MAPLE A208355_list := proc(len) local D, b, h, R, i, k;     D := [seq(0, j=0..len+2)]; D[1] := 1; b := true; h := 2; R := NULL;     for i from 1 to 2*len do         if b then             for k from h by -1 to 2 do D[k] := D[k] - D[k-1] od;             h := h + 1; R := R, abs(D[2]);         else             for k from 1 by 1 to h do D[k] := D[k] + D[k+1] od;         fi;         b := not b:     od;     return R end: A208355_list(38); # Peter Luschny, Dec 19 2017 MATHEMATICA T[_, 0] = 1; T[n_, 1] := n; T[n_, n_] := T[n - 1, n - 2]; T[n_, k_] /; 1 < k < n := T[n, k] = T[n - 1, k] + T[n - 1, k - 2]; a[n_] := T[n, n]; Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Feb 03 2018, from A208101 *) PROG (Haskell) a208355 n = a208101 n n a208355_list = map last a208101_tabl (MAGMA) [Ceiling(Catalan(n div 2)): n in [1..40]]; // Vincenzo Librandi, Feb 18 2014 CROSSREFS Sequence in context: A285013 A095014 A129996 * A099363 A106181 A098887 Adjacent sequences:  A208352 A208353 A208354 * A208356 A208357 A208358 KEYWORD nonn AUTHOR Reinhard Zumkeller, Mar 04 2012 STATUS approved

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Last modified October 23 01:24 EDT 2018. Contains 316518 sequences. (Running on oeis4.)