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 A129097 #6 Mar 10 2020 15:33:04
%S A129097 1,3,11,51,323,3075,47427,1230787,54772163,4247022531,582413946819,
%T A129097 143061847179203,63604391931367363,51621812365091401667,
%U A129097 77028054123935294320579,212592144046864728487817155
%N A129097 a(n) = A129095(2^n - 1) for n>=1.
%C A129097 b(n)=A129095(n) obeys the recurrence: b(n) = b(n/2) (n even), b(n) = 2*b(n-1) + b(n-2) (n odd >1), with b(1) = 1.
%t A129097 Block[{e = 16, s}, s = Nest[Append[#1, If[EvenQ[#2], #1[[#2/2]], 2 #1[[-1]] + #1[[-2]] ] ] & @@ {#, Length@ # + 1} &, {1}, 2^e]; Array[s[[2^# - 1]] &, e]] (* _Michael De Vlieger_, Mar 10 2020 *)
%o A129097 (PARI)
%Y A129097 Cf. A129095, A129096, A129098, A129099.
%K A129097 easy,nonn
%O A129097 1,2
%A A129097 _Paul D. Hanna_, Apr 11 2007