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 A140131 #16 Jun 26 2024 09:33:49
%S A140131 0,1,2,6,16,35,66,121,203,333,550,902,1473,2401,3896,6330,10264,16619,
%T A140131 26919,43588,70562,114198,184804,299051,483906,783013,1266971,2050038,
%U A140131 3317059,5367143,8684259,14051473,22735799,36787341,59523223,96310634,155833920,252144622
%N A140131 a(n) = a(n-1) + a(n-2) + digsum(a(n-1)) + digsum(a(n-2)), with a(0)=0 and a(1)=1.
%H A140131 Harvey P. Dale, <a href="/A140131/b140131.txt">Table of n, a(n) for n = 0..1000</a>
%p A140131 P:=proc(n) local i,t; t:=[0,1]; for i from 1 to n do t:=[op(t),t[-2]+t[-1]+convert(convert(t[-2],base,10),`+`)+convert(convert(t[-1],base,10),`+`)]; od; print(op(t)); end: P(34); # _Paolo P. Lava_, Jun 25 2024
%t A140131 nxt[{a_,b_}]:=a+b+Total[IntegerDigits[a]]+Total[IntegerDigits[b]]; Transpose[NestList[{Last[#],nxt[#]}&,{0,1},40]][[1]] (* _Harvey P. Dale_, Oct 31 2011 *)
%Y A140131 Cf. A007953, A016052, A047892, A047897-A047900, A047902, A047903, A055263, A134268, A135210, A140132.
%K A140131 easy,nonn,base
%O A140131 0,3
%A A140131 _Paolo P. Lava_ and _Giorgio Balzarotti_, May 09 2008