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A123385 (n!)^2/2. 0
2, 18, 288, 7200, 259200, 12700800, 812851200, 65840947200, 6584094720000, 796675461120000, 114721266401280000, 19387894021816320000, 3800027228275998720000, 855006126362099712000000 (list; graph; refs; listen; history; internal format)
OFFSET

2,1

FORMULA

a(n) = Sum[Product[k, {k, i, n}]*a(i), {i, 0, n - 1}].

MATHEMATICA

f[0] = 0; f[1] = 1; f[n_] := f[n] = Sum[Product[k, {k, i, n}]*f[i], {i, 0, n - 1}] Table[f[n], {n, 0, 30}]

CROSSREFS

Sequence in context: A127134 A131455 A084947 * A121564 A092563 A192555

Adjacent sequences:  A123382 A123383 A123384 * A123386 A123387 A123388

KEYWORD

nonn

AUTHOR

Gary Adamson (qntmpkt(AT)yahoo.com), Oct 13 2006

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Last modified February 14 16:19 EST 2012. Contains 205635 sequences.