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 A134069 #17 Feb 16 2025 08:33:06
%S A134069 11,211,853211
%N A134069 Primes in A038399.
%C A134069 A038399 = {1, 11, 211, 3211, 53211, 853211, 13853211, 2113853211, ...} = concatenation of first n nonzero Fibonacci numbers in reverse order.
%C A134069 From _Robert Israel_, Sep 14 2016: (Start)
%C A134069 No more terms < A038399(500), which has 26252 digits.
%C A134069 The probability of a number of the order of magnitude of A038399(n) being prime is approximately constant/n^2. Since Sum_n 1/n^2 converges, we should expect this sequence to be finite. (End)
%H A134069 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/FibonacciNumber.html">Fibonacci Number</a>
%H A134069 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/SmarandacheSequences.html">Smarandache Sequences</a>
%p A134069 count:= 0:
%p A134069 A038399[1]:= 1:
%p A134069 for n from 2 to 100 do
%p A134069 A038399[n]:= combinat:-fibonacci(n)*10^(1+ilog10(A038399[n-1]))+A038399[n-1];
%p A134069 if isprime(A038399[n]) then count:= count+1; A[count]:= A038399[n] fi
%p A134069 od:
%p A134069 seq(A[i],i=1..count); # _Robert Israel_, Sep 14 2016
%t A134069 Module[{nn=10,bif},bif=Fibonacci[Range[nn]];Select[Table[FromDigits[ Flatten[ IntegerDigits/@Reverse[Take[bif,n]]]],{n,nn}],PrimeQ]] (* _Harvey P. Dale_, Sep 27 2019 *)
%Y A134069 Cf. A038399 (concatenation of first n nonzero Fibonacci numbers in reverse order).
%Y A134069 Cf. A019523 (concatenation of Fibonacci numbers).
%K A134069 bref,hard,more,nonn,base
%O A134069 1,1
%A A134069 _Alexander Adamchuk_, Oct 06 2007