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 A078280 #6 May 17 2020 02:23:10
%S A078280 2,212,22122,2258577,18913180982,189219046321892,1893099641364512802,
%T A078280 18935542777368728158257,189400886865505550637253712,
%U A078280 1894918005023238233732500894622,19367362777550568701870550728176482,193719500503687550659615507369001321937,1937649596364149143005250529144645910417392
%N A078280 a(n) = A078279(n)/22.
%o A078280 (PARI) a(n) = {my(c=vector(n), d=0, v=w=[4]); forcomposite(i=4, 4*n, c[d++]=i; if(d==n, break)); for(i=2, n, v=concat(v, d=digits(c[i])); w=concat(d, w)); fromdigits(vector(2*#v, i, if(i%2, v[1+i\2], w[i/2])))/22; } \\ _Jinyuan Wang_, May 17 2020
%Y A078280 Cf. A078278, A078279, A078281.
%K A078280 nonn,base
%O A078280 1,1
%A A078280 _Amarnath Murthy_, Nov 25 2002
%E A078280 More terms from _Jinyuan Wang_, May 17 2020