A106243 Triangle read by rows from left to right. However, triangle is constructed in the boustrophedon way, reading alternately right to left and left to right. Top entry is 1. In all later rows, initial entry is 0, other entries are sum of previous entry in that row plus sum of two entries above it in previous row.

1, 0, 1, 1, 1, 0, 0, 2, 3, 3, 13, 13, 11, 6, 0, 0, 26, 50, 67, 73, 73, 505, 505, 479, 403, 286, 146, 0, 0, 1010, 1994, 2876, 3565, 3997, 4143, 4143, 39313, 39313, 38303, 35299, 30429, 23988, 16426, 8286, 0, 0, 78626, 156242, 229844, 295572, 349989, 390403

Offset

0,8

Links

Table of n, a(n) for n=0..51.

Example

Triangle begins:
            1
          0   1
        1   1   0
      0   2   3   3
   13  13  11   6   0   (e.g., 11 = 6 + 3 + 2)
  0  26  50  67  73  73 (e.g., 50 = 26 + 13 + 11)

Maple

T[0, 0]:=1: for n from 0 to 12 do T[n, -1]:=0 od: for n from 0 to 12 do T[n, n+1]:=0 od: for n from 1 by 2 to 12 do T[n, 0]:=0: for k from 1 to n do T[n, k]:=T[n, k-1]+T[n-1, k]+T[n-1, k-1] od: T[n+1, n+1]:=0: for j from 1 to n+1 do T[n+1, n+1-j]:=T[n+1, n+2-j]+T[n, n+1-j]+T[n, n-j] od: od: for n from 0 to 9 do seq(T[n, k], k=0..n) od; # yields sequence in triangular form; not necessarily the best Maple program # Emeric Deutsch, Aug 03 2005

Crossrefs

Cf. A007318, A008280, A008281, A106242. The row ends give A059294. Row sums give A106327.

Sequence in context: A184178 A350531 A039793 * A109203 A362641 A039792

Adjacent sequences: A106240 A106241 A106242 * A106244 A106245 A106246

Keyword

nonn,tabl,easy

Author

N. J. A. Sloane, May 29 2005

Extensions

More terms from Emeric Deutsch, Aug 03 2005

Status

approved