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 A210714 #11 Jan 27 2020 07:36:52
%S A210714 0,0,0,0,0,0,0,0,1,1,1,1,3,2,5,3,15,5,44,10,203,47,1415,1710,27771,
%T A210714 197951,2613710,33117920,463707092,6709514282,102306345333,
%U A210714 1597440872721
%N A210714 Number of disconnected regular simple graphs on n vertices with girth exactly 4.
%H A210714 Jason Kimberley, <a href="/wiki/User:Jason_Kimberley/D_k-reg_girth_eq_g_index">Index of sequences counting disconnected k-regular simple graphs with girth exactly g</a>
%F A210714 a(n) = A185214(n) - A185215(n).
%t A210714 A[s_Integer] := With[{s6 = StringPadLeft[ToString[s], 6, "0"]}, Cases[ Import["https://oeis.org/A" <> s6 <> "/b" <> s6 <> ".txt", "Table"], {_, _}][[All, 2]]];
%t A210714 A185214 = A@185214;
%t A210714 A185215 = A@185215;
%t A210714 a[n_] := A185214[[n + 1]] - A185215[[n + 1]];
%t A210714 a /@ Range[0, 31] (* _Jean-François Alcover_, Jan 27 2020 *)
%K A210714 nonn,more,hard
%O A210714 0,13
%A A210714 _Jason Kimberley_, Dec 10 2012
%E A210714 a(31) corrected by the author, propagated from A185244, Jan 05 2013