A008308 Triangle of tangent numbers.

1, 1, 2, 1, 8, 1, 16, 20, 1, 136, 40, 1, 272, 616, 70, 1, 3968, 2016, 112, 1, 7936, 28160, 5376, 168, 1, 176896, 135680, 12432, 240, 1, 353792, 1805056, 508640, 25872, 330, 1, 11184128, 11977856, 1595264, 49632, 440, 1, 22368256, 154918400, 59835776

Offset

1,3

References

L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 259.

Links

Table of n, a(n) for n=1..45.

Example

Triangle begins:
    1;
    1;
    2,  1;
    8,  1;
   16, 20, 1;
  136, 40, 1;
  ...

Mathematica

T[n_, n_] = 1; T[n_, k_] /; 0 <= k <= n := T[n, k] = T[n - 1, k - 1] + k*(k + 1)*T[n - 1, k + 1]; T[_, _] = 0;
row[n_] := DeleteCases[Table[T[n, k], {k, 1, n}] , 0];
Array[row, 13] // Flatten (* Jean-François Alcover, Nov 09 2017 *)

Crossrefs

Essentially the same triangle as A059419, which is the main entry for this triangle.

Row sums give A006229.

Sequence in context: A369779 A125911 A009385 * A176889 A208753 A118931

Adjacent sequences: A008305 A008306 A008307 * A008309 A008310 A008311

Keyword

tabf,nonn,nice

Author

N. J. A. Sloane

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), Feb 08 2001

Status

approved