A123264 Pascal's reversal triangle, read by rows.

1, 1, 1, 1, 2, 1, 1, 3, 3, 1, 1, 4, 6, 4, 1, 1, 5, 1, 1, 5, 1, 1, 6, 6, 2, 6, 6, 1, 1, 7, 21, 8, 8, 21, 7, 1, 1, 8, 82, 92, 61, 92, 82, 8, 1, 1, 9, 9, 471, 351, 351, 471, 9, 9, 1, 1, 1, 81, 84, 228, 207, 228, 84, 81, 1, 1, 1, 2, 28, 561, 213, 534, 534, 213, 561, 28, 2, 1, 1, 3, 3, 985, 477

Offset

1,5

Comments

Each value is the digital reversal of the sum of the value above and to the left with the value above and to the right. Central coefficients T(2n,n) = 1, 2, 6, 2, 61, 207, 8601, 87861,...

Links

Table of n, a(n) for n=1..83.

Formula

T(0,1) = 1; T(1,1) = T(1,2) = 1; for i>1, T(i,j) = R(T(i-1,j-1)+T(i-1,j)) = A004086(T(i-1,j-1)+T(i-1,j)).

Example

Triangle begins:
...........1
..........1.1
.........1.2.1
........1.3.3.1
.......1.4.6.4.1
......1.5.1.1.5.1
.....1.6.6.2.6.6.1
...1.7.21.8.8.21.7.1
.1.8.82.92.61.92.82.8.1

Crossrefs

Cf. A004086, A007318.

Sequence in context: A140279 A096145 A306309 * A034930 A095142 A180171

Adjacent sequences: A123261 A123262 A123263 * A123265 A123266 A123267

Keyword

base,easy,nonn,tabl

Author

Jonathan Vos Post, Nov 07 2006

Status

approved