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 A340259 #14 Jan 09 2021 15:41:14
%S A340259 1,0,14,870,18796230,28634752793916486,
%T A340259 187118328452563149209991044344449606,
%U A340259 22533823529098462258163079522899558179092788838542277982316450977506091590
%N A340259 a(n) = A340312(n, 2^(n-1)). a(n) is the central term of row n of A340312.
%C A340259 a(9) = 2299131884087642202247291403507120751687796592498104258 * C, where C is a composite factor with 96 digits.
%C A340259 C = P47*P49, with P47 = 88967307877356450624418823383132738084943851019 and
%C A340259 P49 = 4512180962860489443011495305279720577473472225641. - _Hugo Pfoertner_, Jan 09 2021
%H A340259 Andrew Howroyd, <a href="/A340259/b340259.txt">Table of n, a(n) for n = 1..11</a>
%F A340259 a(n) = (2*binomial(2^n-1, 2^(n-1)) + (2^n-1)*binomial(2^(n-1), 2^(n-2)))/2^n for n >= 3. - _Andrew Howroyd_, Jan 09 2021
%p A340259 seq(A340312_row(n)[2^(n-1)+1], n = 1..8);
%o A340259 (PARI) a(n) = {if(n<=2, n==1, (2*binomial(2^n-1, 2^(n-1)) + (2^n-1)*binomial(2^(n-1), 2^(n-2)))/2^n)} \\ _Andrew Howroyd_, Jan 09 2021
%Y A340259 Cf. A340312, A340263.
%K A340259 nonn
%O A340259 1,3
%A A340259 _Peter Luschny_, Jan 06 2021