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 A092285 #13 Feb 29 2020 15:43:57
%S A092285 1,4,12,22,65,116,399,554,2475,3232,14938,20208,101413,130846,691890,
%T A092285 924946,4867559,6281552,35154066,46902128,253485141,328375720,
%U A092285 1877693458,2504042868,13754442225,17885555976,103317302754,137761862662,765705075439,998817493980
%N A092285 Number of productions of a certain "divide-and-conquer" context-free grammar in Chomsky normal form that generates all permutations of n symbols.
%H A092285 Andrew Howroyd, <a href="/A092285/b092285.txt">Table of n, a(n) for n = 1..200</a>
%H A092285 P. R. J. Asveld, <a href="http://dx.doi.org/10.1016/j.tcs.2005.11.010">Generating all permutations by context-free grammars in Chomsky normal form</a>, Theoretical Computer Science 354 (2006) 118-130.
%F A092285 a(n) = Sum_{k=1..n} t(n, k)*C(k, ceiling(k/2)), where t(n, k) is the n-th row in the Pascal-like triangle of A090349 and C(k, i) is the binomial coefficient.
%e A092285 a(4) = 4*C(1,1) + 6*C(2,1) + 0*C(3,2) + 1*C(4,2) = 4 + 12 + 0 + 6 = 22; cf. the example grammar in A090349.
%o A092285 (PARI) a(n)={my(b=vector(n)); for(i=0, logint(n,2), b[n>>i]=1; b[((n-1)>>i)+1]=1); sum(k=1, n, b[k]*binomial(n,k)*binomial(k,k\2))} \\ _Andrew Howroyd_, Feb 29 2020
%Y A092285 Cf. A090349.
%K A092285 nonn
%O A092285 1,2
%A A092285 _Peter R. J. Asveld_, Jan 30 2004
%E A092285 Terms a(21) and beyond from _Andrew Howroyd_, Feb 29 2020