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 A156791 #17 Jun 12 2021 23:20:58
%S A156791 1,1,6,7,78,420,6872,17253,326552,2680988,33949242,386091406,
%T A156791 5974089338,67562271804,1708769998136,16983594666421,329723068729854,
%U A156791 5611760457560028,121573316570762036,2099347805249971662,50720938223339101844,1008798617234428297708
%N A156791 INVERTi transform of A006973.
%H A156791 G. C. Greubel, <a href="/A156791/b156791.txt">Table of n, a(n) for n = 1..440</a>
%F A156791 INVERTi transform of (A006973 with offset 1) = (1, 2, 9, 24, 130, 720, ...).
%F A156791 Coefficients of ( S(n, x)/(x + S(n, x)) ), where S(n, x) = Sum_{j=0..n+2} A006973(j)*x^j. - _G. C. Greubel_, Jun 10 2021
%e A156791 The sequence begins (1, 1, ...); then for all further a(n), write (n-1) terms of A006973 backwards. Take the dot of the latter and the first (n-1) terms of sequence. Subtract from the next term of A006973.
%e A156791 Example: a(4) = 7 = (24 - (9, 2, 1) dot (1, 1, 6)) = 24 - 17.
%t A156791 A006973[n_]:= A006973[n]= If[n<4, Max[n-1, 0], (n-1)!*(1 + Sum[k*(-A006973[k]/k!)^(n/k), {k, Most[Divisors[n]]}])];
%t A156791 S[n_, x_]:= Sum[A006973[j]*x^j, {j, 0, n+2}];
%t A156791 Rest@With[{p = 100}, CoefficientList[Series[S[p,x]/(x + S[p,x]), {x,0,60}], x]] (* _G. C. Greubel_, Jun 10 2021 *)
%Y A156791 Cf. A006973, A156792.
%K A156791 nonn
%O A156791 1,3
%A A156791 _Gary W. Adamson_, Feb 15 2009
%E A156791 Terms a(11) onward added by _G. C. Greubel_, Jun 10 2021