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 A289830 #30 May 02 2020 02:42:08
%S A289830 -1,2,18,124,900,7188,63504,618336,6596640,76635360,963895680,
%T A289830 13056819840,189581333760,2938083321600,48416639846400,
%U A289830 845487698227200,15598004134809600,303161985274982400,6191998554470400000,132599321499875328000,2970952207377960960000
%N A289830 a(n) satisfies the equation n/(n-1) + a(n)/n! = H(n), where H(n) is the n-th harmonic number.
%F A289830 a(n) = n! * (H(n) - n/(n-1)). - _Alois P. Heinz_, Jul 13 2017
%t A289830 Table[n!*(HarmonicNumber[n] - n/(n - 1)), {n, 2, 22}] (* _Michael De Vlieger_, Jul 13 2017 *)
%o A289830 (Python)
%o A289830 from sympy import factorial, harmonic
%o A289830 def a(n): return factorial(n-2)*(harmonic(n)*(n-1) - n)*n
%o A289830 print([a(n) for n in range(2, 26)]) # _Indranil Ghosh_, Jul 14 2017
%Y A289830 Cf. A001008, A002805.
%K A289830 sign
%O A289830 2,2
%A A289830 _Joseph Wheat_, Jul 12 2017
%E A289830 More terms from _Alois P. Heinz_, Jul 13 2017