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 A129465 #15 Feb 09 2024 03:04:39
%S A129465 1,1,-4,-204,-7776,-358560,-20839680,-1516112640,-135920332800,
%T A129465 -14772931891200,-1917601910784000,-293337284308992000,
%U A129465 -52263416690343936000,-10734227287227924480000,-2518467729187335045120000,-669569466986357627289600000
%N A129465 Third column (m=2) sequence of triangle A129462 (v=2 member of a certain family).
%C A129465 See A129462 for the M. Bruschi et al. reference.
%H A129465 G. C. Greubel, <a href="/A129465/b129465.txt">Table of n, a(n) for n = 0..250</a>
%F A129465 a(n) = A129462(n+2, 2), n >= 0.
%F A129465 a(n) = (-1)*n!*(n+2)!*(HarmonicNumber(n+2) - 2), for n >= 1, otherwise a(0) = 1. - _G. C. Greubel_, Feb 08 2024
%t A129465 A129465[n_]:= If[n==0, 1, -n!*(n+2)!*(HarmonicNumber[n+2] -2)];
%t A129465 Table[A129465[n], {n,0,30}] (* _G. C. Greubel_, Feb 08 2024 *)
%o A129465 (Magma)
%o A129465 A129465:= func< n | n eq 0 select 1 else -Factorial(n)*Factorial(n+2)*(HarmonicNumber(n+2) -2) >;
%o A129465 [A129465(n): n in [0..30]]; // _G. C. Greubel_, Feb 08 2024
%o A129465 (SageMath)
%o A129465 def A129465(n): return 1 if (n==0) else -factorial(n)*factorial(n+2)*( harmonic_number(n+2) -2)
%o A129465 [A129465(n) for n in range(31)] # _G. C. Greubel_, Feb 08 2024
%Y A129465 Cf. A129462, A129464 (m=1), A129466(m=3).
%K A129465 sign,easy
%O A129465 0,3
%A A129465 _Wolfdieter Lang_, May 04 2007