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 A307593 #9 Jun 11 2022 20:18:16
%S A307593 1,3,10,39,180,977,6156,44401,361872,3295025,33193284,366828033,
%T A307593 4414938000,57501795977,805984165252,12098920460089,193676009792768,
%U A307593 3293501718960033,59294599560573508,1126737323074730161,22536528123718353104,473290909667471110361
%N A307593 Expansion of e.g.f. (sec(x) + tan(x))*exp(x)/(1 - x).
%C A307593 Boustrophedon transform of A000522.
%H A307593 <a href="/index/Bo#boustrophedon">Index entries for sequences related to boustrophedon transform</a>
%t A307593 nmax = 21; CoefficientList[Series[(Sec[x] + Tan[x]) Exp[x]/(1 - x), {x, 0, nmax}], x] Range[0, nmax]!
%t A307593 t[n_, 0] := If[n < 1, 1, Floor[Exp[1] n!]]; t[n_, k_] := t[n, k] = t[n, k - 1] + t[n - 1, n - k]; a[n_] := t[n, n]; Array[a, 22, 0]
%o A307593 (Python)
%o A307593 from itertools import count, islice, accumulate
%o A307593 def A307593_gen(): # generator of terms
%o A307593 blist, m = tuple(), 1
%o A307593 for i in count(1):
%o A307593 yield (blist := tuple(accumulate(reversed(blist),initial=m)))[-1]
%o A307593 m = m*i + 1
%o A307593 A307593_list = list(islice(A307593_gen(),30)) # _Chai Wah Wu_, Jun 11 2022
%Y A307593 Cf. A000111, A000522, A230960, A307594.
%K A307593 nonn
%O A307593 0,2
%A A307593 _Ilya Gutkovskiy_, Apr 17 2019