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 A102181 #13 Mar 23 2023 17:30:19
%S A102181 5,11,12,17,18,37,38,43,44,45,55,61,70,93,103,110,120,129,174,198,241,
%T A102181 245,277,303,342,381,393,552,590,657,708
%N A102181 Iccanobirt semiprime indices (11 of 15): Indices of semiprime numbers in A102121.
%F A102181 A102121(a(n)) = A102201(n).
%t A102181 nxt[{a_,b_,c_}]:={b,c,IntegerReverse[c+IntegerReverse[b]+IntegerReverse[a]]}; Flatten[ Position[NestList[nxt,{0,0,1},800][[;;,1]],_?(PrimeOmega[#]==2&)]-1] (* _Harvey P. Dale_, Mar 23 2023 *)
%Y A102181 Cf. A001358, A102121, A102171-A102185, A102201.
%K A102181 nonn,more,less,base
%O A102181 1,1
%A A102181 _Jonathan Vos Post_ and _Ray Chandler_, Dec 31 2004
%E A102181 Offset changed to 1 and a(21)-a(31) from _Jinyuan Wang_, Aug 14 2021