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

Author

N. J. A. Sloane, May 29 2005

Keywords

• nonn
• tabl
• easy

Examples

			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)
		

Crossrefs

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

Programs

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

Extensions

More terms from Emeric Deutsch, Aug 03 2005