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A084980 Triangle of (multi)factorials: n-th row is (n+1)!!... {n "!"s}, (n+1)!... {n-1 "!"s}, ..., (n+1)!. 2
2, 3, 6, 4, 8, 24, 5, 10, 15, 120, 6, 12, 18, 48, 720, 7, 14, 21, 28, 105, 5040, 8, 16, 24, 32, 80, 384, 40320, 9, 18, 27, 36, 45, 162, 945, 362880, 10, 20, 30, 40, 50, 120, 280, 3840, 3628800, 11, 22, 33, 44, 55, 66, 231, 880, 10395, 39916800, 12, 24, 36, 48, 60, 72, 168 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Ivan Neretin, Table of n, a(n) for n = 1..4950

Eric Weisstein's World of Mathematics, Factorial.

Eric Weisstein's World of Mathematics, Multifactorial.

EXAMPLE

Triangle begins

Row 1: 2! = 2

Row 2: 3!! = 3*1 = 3, 3! = 3*2*1 = 6

Row 3: 4!!! = 4*1 = 4, 4!! = 4*2 = 8, 4! = 4*3*2*1 = 24,

Row 4: 5!!!! = 5*1 = 5, 5!!! = 5*2 = 10, 5!! = 5*3 = 15, 5! = 5*4*3*2*1 = 120,

...

MATHEMATICA

Flatten[Table[Times @@ Range[n, 1, -i], {n, 12}, {i, n - 1, 1, -1}]] (* Ivan Neretin, May 09 2015 *)

CROSSREFS

Cf. A000142 (n!), A006882 (n!!), A007661 (n!!!), A007662 (n!!!!).

Sequence in context: A052330 A059900 A123664 * A101369 A125147 A103864

Adjacent sequences:  A084977 A084978 A084979 * A084981 A084982 A084983

KEYWORD

nonn,tabl

AUTHOR

Rick L. Shepherd, Jul 16 2003

STATUS

approved

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Last modified April 11 03:12 EDT 2021. Contains 342886 sequences. (Running on oeis4.)