This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A193282 #19 Sep 08 2022 08:45:58 %S A193282 1,1,4,36,144,3600,14400,705600,2822400,228614400,914457600, %T A193282 110649369600,442597478400,74798973849600,299195895398400, %U A193282 67319076464640000,269276305858560000,77820852393123840000,311283409572495360000,112373310855670824960000 %N A193282 a(n) = (n!/floor(n/2)!)^2. %H A193282 Vincenzo Librandi, <a href="/A193282/b193282.txt">Table of n, a(n) for n = 0..400</a> %F A193282 a(n) = A056040(n)*A000142(n). %F A193282 a(n) = A081125(n)^2. %F A193282 a(n) = Sum_{k=0..n} (-1)^(n-k)*binomial(n,k)*A195009(n,k). %F A193282 a(n) = n!^2*[x^n] (1+x)*BesselI(0,2*x). Here [x^n]f(x) denotes the coefficient of x^n in f(x). %F A193282 Conjecture: a(n) + 8*a(n-1) - 4*(n-2)*(n+2)*a(n-2) + 16*(-2*n^2 + 6*n - 3)*a(n-3) - 64*(n-3)^2*a(n-4) = 0. - _R. J. Mathar_, Oct 03 2014 %p A193282 A193282 := n -> (n!/iquo(n,2)!)^2; %t A193282 Table[(n!/(Floor[n/2]!))^2,{n,0,20}] (* _Harvey P. Dale_, Jul 30 2020 *) %o A193282 (Magma) [(Factorial(n)/Factorial(Floor(n/2)))^2: n in [0..20]]; // _Vincenzo Librandi_, Sep 11 2011 %Y A193282 Cf. A000142, A056040, A195009. %K A193282 nonn %O A193282 0,3 %A A193282 _Peter Luschny_, Sep 08 2011