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 A129091 #9 Mar 04 2018 17:44:30 %S A129091 1,2,4,13,53,266,800,5601,44809,403282,2016412,22180533,88722135, %T A129091 1153387756,8073714294,40368571473,645897143569,10980251440674, %U A129091 32940754322028,625874332118533,12517486642370661,12517486642370682 %N A129091 a(0)=1; a(n) = gcd(a(n-1), n) + lcm(a(n-1), n). %p A129091 a[0]:=1: for n from 1 to 25 do a[n]:=gcd(a[n-1],n)+lcm(a[n-1],n) od: seq(a[n],n=0..25); # _Emeric Deutsch_, Apr 02 2007 %Y A129091 Cf. A129090. %K A129091 nonn %O A129091 0,2 %A A129091 _Leroy Quet_, Mar 29 2007 %E A129091 More terms from _Emeric Deutsch_, Apr 02 2007