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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 G. C. Greubel, Table of n, a(n) for n = 0..500 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 Cf. A000079, A006882. Sequence in context: A062474 A073999 A259056 * A370305 A355645 A323941 Adjacent sequences: A155157 A155158 A155159 * A155161 A155162 A155163 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.)