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 A259225 #19 Aug 16 2022 03:06:47
%S A259225 0,2,2,6,6,6,6,12,12,12,12,12,12,20,20,20,20,20,20,20,20,30,30,30,30,
%T A259225 30,30,30,30,30,30,42,42,42,42,42,42,42,42,42,42,42,42,56,56,56,56,56,
%U A259225 56,56,56,56,56,56,56,56,56,72,72,72,72,72,72,72,72,72,72
%N A259225 Smallest oblong number greater than or equal to n.
%H A259225 Casey Douglas, <a href="https://web.archive.org/web/20150912213402/https://mathematicalypse.wordpress.com/2012/06/24/the-next-square-or-pronic/">The Next Square or Pronic</a>, June 2012. [Wayback Machine copy]
%F A259225 Sum_{n>=1} 1/a(n)^2 = 4 - Pi^2/3. - _Amiram Eldar_, Aug 16 2022
%t A259225 f[n_] := n*(n + 1); g[n_] := (Sqrt[4*n + 1] - 1)/2; a[n_] := f[Ceiling[g[n]]]; Array[a, 100, 0] (* _Amiram Eldar_, Aug 16 2022 *)
%o A259225 (PARI) a(n) = my(k = 0); while(k*(k+1)<n, k++); k*(k+1);
%Y A259225 Cf. A002378 (oblong numbers), A048761 (similar, with square instead).
%K A259225 nonn
%O A259225 0,2
%A A259225 _Michel Marcus_, Jun 21 2015