A059227 Last entry in n-th row of triangle defined in A059226.

1, 1, 4, 18, 94, 544, 3370, 21878, 146924, 1012222, 7114218, 50808592, 367669254, 2689974234, 19864822564, 147875395930, 1108469655350, 8359790718480, 63387403235682, 482935966313310, 3695204342149004, 28383451250732662

Offset

0,3

Links

G. C. Greubel, Table of n, a(n) for n = 0..250

Index entries for sequences related to boustrophedon transform

Mathematica

T[i_, j_] := T[i, j] = Module[{r, s, t1}, If[i == 0 && j == 0, Return[1]];
If[j == 0, Return[0]]; t1 = T[i, j - 1]; For[r = 0, r <= i - j, r++,
For[s = 0, s <= j, s++, If[r + s != i, t1 = t1 + T[r + s, s]]]];
Return[t1]]; Table[T[n, n], {n, 0, 25}] (* G. C. Greubel, Jan 03 2017 *)
Join[{1}, CoefficientList[Nest[1+(3x-x^2)#+(x-x^2)#^2&, 1+O[x], 20], x]] (* Oliver Seipel, Dec 28 2024 *)

Crossrefs

Sequence in context: A209256 A367282 A364475 * A259533 A305239 A370344

Adjacent sequences: A059224 A059225 A059226 * A059228 A059229 A059230

Keyword

nonn

Author

N. J. A. Sloane, Jan 19 2001

Status

approved