A203482 a(n) = Product_{1 <= i < j <= n} (i! + j!).
1, 3, 168, 3276000, 877449500928000, 207244701437748852512194560000, 4000516840149319128119305958853265913416777728000000, 796608816253064941944831363792070377592412324940256242675178274726476775424000000000
Offset: 1
Keywords
Links
- G. C. Greubel, Table of n, a(n) for n = 1..16
Programs
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Magma
[(&*[(&*[Factorial(j) + Factorial(k): k in [1..j]])/(2*Factorial(j)): j in [1..n]]): n in [1..20]]; // G. C. Greubel, Aug 29 2023
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Maple
a:= n-> mul(mul(i!+j!, i=1..j-1), j=2..n): seq(a(n), n=1..10); # Alois P. Heinz, Jul 23 2017
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Mathematica
(* First program *) f[j_]:= j!; z = 10; v[n_]:= Product[Product[f[k] + f[j], {j, k-1}], {k, 2, n}] d[n_]:= Product[(i-1)!, {i, n}] (* A000178 *) Table[v[n], {n, z}] (* A203482 *) Table[v[n+1]/v[n], {n, z-1}] (* A203483 *) Table[v[n]/d[n], {n, 10}] (* A203510 *) (* Second program *) Table[Product[j!+k!, {j,n}, {k,j-1}], {n,15}] (* G. C. Greubel, Aug 29 2023 *)
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SageMath
[product(product(factorial(j) + factorial(k) for k in range(1,j)) for j in range(1,n+1)) for n in range(1,16)] # G. C. Greubel, Aug 29 2023
Formula
a(n) ~ c * n^(n^3/3 + n^2/4 - 7*n/12 + 5/8) * (2*Pi)^(n*(n-1)/4) / exp(4*n^3/9 - n^2/8 - n), where c = 0.488888619502150098591650327163991582267254151817880403495924251381414248582... - Vaclav Kotesovec, Nov 20 2023
Extensions
Name edited by Alois P. Heinz, Jul 23 2017
Comments