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A155160 a(n) = 2^n * (n + 3)!!. 1
3, 16, 60, 384, 1680, 12288, 60480, 491520, 2661120, 23592960, 138378240, 1321205760, 8302694400, 84557168640, 564583219200, 6088116142080, 42908324659200, 487049291366400, 3604299271372800, 42860337640243200 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,1
LINKS
FORMULA
a(n) = 2^n*(n+3)!!.
From G. C. Greubel, Mar 19 2021: (Start)
a(2*n) = 2^(n-1)*(2*n+3)!/(n+1)!.
a(2*n+1) = 2^(4*n+3)*(n+2)!. (End)
MATHEMATICA
Table[2^n*(n+3)!!, {n, 0, 30}]
Table[2^n*If[EvenQ[n], (n+3)!/(2^(n/2+1)*(n/2+1)!), 2^((n+3)/2)*((n+3)/2)!], {n, 0, 30}] (* G. C. Greubel, Mar 19 2021 *)
PROG
(Magma) [(n mod 2) eq 0 select Round(2^(n)*Factorial(n+3)/(2^(n/2+1)*Gamma((n+4)/2))) else Round(2^(n+(n+3)/2)*Gamma((n+5)/2)): n in [0..30]]; // G. C. Greubel, Mar 19 2021
(Sage) [2^n*(n+3).multifactorial(2) for n in (0..30)] # G. C. Greubel, Mar 19 2021
CROSSREFS
Sequence in context: A062474 A073999 A259056 * A370305 A355645 A323941
KEYWORD
nonn
AUTHOR
Roger L. Bagula, Jan 21 2009
STATUS
approved

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Last modified June 20 13:44 EDT 2024. Contains 373527 sequences. (Running on oeis4.)