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 A102137 #19 Nov 09 2018 22:12:39
%S A102137 4,6,7,19,43,48,109,122,628,1689,6208,6309,15479,21651
%N A102137 Iccanobirt prime indices (7 of 15): Indices of prime numbers in A102117.
%C A102137 a(15) > 50000. - _Robert Price_, Nov 09 2018
%F A102137 A102117(a(n)) = A102157(n).
%p A102137 rev:= proc(n) local i, L;
%p A102137 L:= convert(n,base, 10);
%p A102137 add(L[-i]*10^(i-1),i=1..nops(L))
%p A102137 end proc:
%p A102137 A[0]:= 0: A[1]:= 0: A[2]:= 1:
%p A102137 RA[0]:=0: RA[1]:= 0: RA[2]:= 1:
%p A102137 count:= 0:
%p A102137 for n from 3 to 10000 do
%p A102137 A[n]:= RA[n-1]+RA[n-2]+RA[n-3];
%p A102137 RA[n]:= rev(A[n]);
%p A102137 if isprime(A[n]) then count:= count+1; a[count]:= n fi
%p A102137 od:
%p A102137 seq(a[i],i=1..count); # _Robert Israel_, Aug 04 2016
%t A102137 Flatten[Position[Transpose[NestList[nxt,{0,0,1},1700]][[1]],_?PrimeQ]]-1 (* _Harvey P. Dale_, Nov 28 2015 *)
%Y A102137 Cf. A000040, A102117, A102131-A102145.
%K A102137 nonn,more,base
%O A102137 1,1
%A A102137 _Jonathan Vos Post_ and _Ray Chandler_, Dec 31 2004
%E A102137 a(11)-a(13) from _Robert Israel_, Aug 04 2016
%E A102137 a(14) from _Robert Price_, Nov 09 2018