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 A175925 #24 Sep 08 2022 08:45:52
%S A175925 1,6,30,168,1080,7920,65520,604800,6168960,68947200,838252800,
%T A175925 11017036800,155675520000,2353813862400,37922556672000,
%U A175925 648606486528000,11737685127168000,224083079700480000,4500868715126784000
%N A175925 a(n) = (2*n+1)*(n+1)!.
%C A175925 The denominators of the Taylor expansion coefficients of the double integral d(u) = int_0^1 dx int_0^1 dy exp(-u^2*(x-y)^2) = Sum_{n>=0} (-1)^n*u^(2n)/a(n).
%H A175925 Vincenzo Librandi, <a href="/A175925/b175925.txt">Table of n, a(n) for n = 0..400</a>
%H A175925 D. H. Bailey, J. M. Borwein, R. E. Crandall, <a href="http://dx.doi.org/10.1090/S0025-5718-10-02338-0">Advances in the theory of box integrals</a>, Math. Comp. 79 (271) (2010) 1839-1866, eq (18).
%H A175925 Milan Janjić, <a href="https://www.emis.de/journals/JIS/VOL21/Janjic2/janjic103.html">Pascal Matrices and Restricted Words</a>, J. Int. Seq., Vol. 21 (2018), Article 18.5.2.
%F A175925 a(n) = A005408(n)*A000142(n+1) = (n+1)*A007680(n).
%F A175925 E.g.f.: (1 + 3*x)/(1 - x)^3. - _Ilya Gutkovskiy_, May 12 2017
%F A175925 From _Amiram Eldar_, Aug 04 2020: (Start)
%F A175925 Sum_{n>=0} 1/a(n) = sqrt(Pi)*erfi(1) + 1 - e.
%F A175925 Sum_{n>=0} (-1)^n/a(n) = sqrt(Pi)*erf(1) - 1 + 1/e. (End)
%p A175925 A := proc(n) (2*n+1)*(n+1)! ; end proc:
%t A175925 Table[(2n+1)(n+1)!,{n,0,20}] (* _Harvey P. Dale_, Sep 30 2011 *)
%o A175925 (Magma) [(2*n+1)*Factorial(n+1): n in [0..20]]; // _Vincenzo Librandi_, Oct 11 2011
%Y A175925 Cf. A000142, A005408, A007680.
%K A175925 nonn,easy
%O A175925 0,2
%A A175925 _R. J. Mathar_, Oct 19 2010