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 A129785 #18 Jan 04 2020 02:48:46
%S A129785 1,2,6,70,18886,3534626502,313999279896461576406,
%T A129785 6253297416830848418609522661421870085933646
%N A129785 a(n) = Product_{k=0..n-1} (1 + binomial(n,k)*a(k)), with a(0) = 1.
%C A129785 A product analog of the Bell numbers.
%D A129785 H. W. Gould, A product analog of the Bell numbers, unpublished manuscript, Jun 03 2007.
%H A129785 Andrew Howroyd, <a href="/A129785/b129785.txt">Table of n, a(n) for n = 0..11</a>
%e A129785 a(5) = (1+1)*(1+8)*(1+36)*(1+280)*(1+18886) = 3534626502.
%p A129785 A129785 := proc(n)
%p A129785 a := 1 ;
%p A129785 for k from 0 to n-1 do
%p A129785 a := a*(1+binomial(n-1,k)*procname(k)) ;
%p A129785 end do:
%p A129785 a ;
%p A129785 end proc: # _R. J. Mathar_, Nov 24 2013
%t A129785 a[n_]:= a[n] = Product[1 + Binomial[n-1, k]*a[k], {k, 0, n-1}];
%t A129785 Table[a[n], {n, 0, 10}] (* _Vaclav Kotesovec_, Oct 27 2017 *)
%o A129785 (PARI) a(n)={my(v=vector(n+1)); for(n=0, #v-1, v[1+n]=prod(k=0, n-1, 1 + binomial(n-1, k)*v[1+k])); v[#v]} \\ _Andrew Howroyd_, Jan 03 2020
%K A129785 easy,nonn
%O A129785 0,2
%A A129785 _Henry Gould_, Jun 03 2007