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 A187443 #12 Jan 14 2023 08:46:01
%S A187443 1,6,35,252,1716,12870,92378,705432,5200300,40116600,300540195,
%T A187443 2333606220,17672631900,137846528820,1052049481860,8233430727600,
%U A187443 63205303218876,495918532948104,3824345300380220,30067266499541040,232714176627630544,1832624140942590534,14226520737620288370,112186277816662845432,873065282167813104916
%N A187443 A trisection of A001405 (central binomial coefficients): binomial(3n+1,floor((3n+1)/2)), n>=0.
%C A187443 For trisection of sequences see a comment and a reference under A187357.
%F A187443 a(n) = binomial(3*n+1,floor((3*n+1)/2)), n>=0.
%F A187443 O.g.f.: 3!*x*G2(x^2) + G1(x^2), with G2(x) and G1(x) the o.g.f.s of A187365 and A187364, respectively.
%t A187443 Table[Binomial[3n+1,Floor[(3n+1)/2]],{n,0,30}] (* _Harvey P. Dale_, Jan 13 2021 *)
%Y A187443 Cf. A187442: binomial(3n,floor(3n/2)), A187444: binomial(3n+2,floor((3n+2)/2))/2.
%Y A187443 Cf. A187357, A187364, A187365.
%Y A187443 Cf. A001405.
%K A187443 nonn,easy
%O A187443 0,2
%A A187443 _Wolfdieter Lang_, Mar 10 2011
%E A187443 Corrected and extended by _Harvey P. Dale_, Jan 13 2021