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A156529 A triangular sequence: e(n,k)=(k + 1)e(n - 1, k) + (2n - k - 1)e(n - 1, k - 1); t(n,m)=(e(n, k)*e(n, n - k - 1)). 0
1, 2, 2, 6, 64, 6, 24, 1276, 1276, 24, 120, 23088, 107584, 23088, 120, 720, 422712, 6388800, 6388800, 422712, 720, 5040, 8156160, 326165400, 1031694400, 326165400, 8156160, 5040, 40320, 168521184, 15666814800, 126099116000, 126099116000 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Row sums are:

{1, 4, 76, 2600, 154000, 13624464, 1700347600, 283868984608, 61166882025040,

16525206308179712,...}

LINKS

Table of n, a(n) for n=0..32.

FORMULA

e(n,k)=(k + 1)e(n - 1, k) + (2n - k - 1)e(n - 1, k - 1); t(n,m)=(e(n, k)*e(n, n - k - 1))..

EXAMPLE

{1},

{2, 2},

{6, 64, 6},

{24, 1276, 1276, 24},

{120, 23088, 107584, 23088, 120},

{720, 422712, 6388800, 6388800, 422712, 720},

{5040, 8156160, 326165400, 1031694400, 326165400, 8156160, 5040},

{40320, 168521184, 15666814800, 126099116000, 126099116000, 15666814800, 168521184, 40320},

{362880, 3748855680, 741628668960, 13217568000000, 33240990250000, 13217568000000, 741628668960, 3748855680, 362880},

{3628800, 89830895040, 35494281317376, 1272445743488640, 6954573294760000, 6954573294760000, 1272445743488640, 35494281317376, 89830895040, 3628800}

MATHEMATICA

e[n_, 0] := 1;

e[n_, k_] := 0 /; k >= n;

e[n_, k_] := (k + 1)e[n - 1, k] + (2n - k - 1)e[n - 1, k - 1];

Table[Table[(e[n, k]*e[n, n - k - 1]), {k, 0, n - 1}], {n, 1, 10}];

Flatten[%]

CROSSREFS

A008517

Sequence in context: A174589 A247943 A270358 * A184712 A303225 A304564

Adjacent sequences:  A156526 A156527 A156528 * A156530 A156531 A156532

KEYWORD

nonn,tabl,uned

AUTHOR

Roger L. Bagula, Feb 09 2009

STATUS

approved

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Last modified May 25 19:07 EDT 2019. Contains 323576 sequences. (Running on oeis4.)