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A008308 Triangle of tangent numbers. 1
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 (list; graph; refs; listen; history; text; internal format)
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-Fran├žois 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: A102208 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

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Last modified October 16 17:09 EDT 2018. Contains 316271 sequences. (Running on oeis4.)