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 A135970 #9 May 09 2021 10:56:55
%S A135970 2,13,1346269,155576970220531065681649693
%N A135970 Fibonacci(Mersenne primes): a(n) = Fibonacci(A000668(n)).
%C A135970 This sequence is a subsequence of A101342. The next term, a(5), has 1712 digits.
%t A135970 k = {}; Do[If[PrimeQ[2^n - 1], AppendTo[k, Fibonacci[2^n - 1]]], {n, 1, 15}]; k
%t A135970 Fibonacci/@Select[Table[2^Prime[n]-1,{n,5}],PrimeQ] (* _Harvey P. Dale_, May 06 2018 *)
%Y A135970 Cf. A000045, A000668, A001605, A050937, A075737, A090819, A134787, A134851, A134852, A135953, A135954, A135955, A135956, A135957, A135958, A135959, A135968, A135969, A101342.
%K A135970 nonn
%O A135970 1,1
%A A135970 _Artur Jasinski_, Dec 09 2007