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 A090206 #24 Jul 05 2022 11:10:28 %S A090206 0,1,1,8,21,34,55,144,377,610,987,2584,4181,6765,10946,17711,46368, %T A090206 75025,121393,196418,317811,832040,1346269,2178309,3524578,5702887, %U A090206 9227465,14930352,24157817,39088169 %N A090206 Nonprime Fibonacci numbers. %C A090206 It is possible to find a run of at least length n (not necessarily exactly n) such that n consecutive terms in this sequence are also consecutive in the sequence of Fibonacci numbers. However, it is not possible for such a run to be of exactly length n if n is even. - _Alonso del Arte_, Nov 23 2010 %C A090206 Some terms of this sequence have prime indices in the sequence of Fibonacci numbers (A000045), see A050937. - _Alonso del Arte_, Aug 16 2013 %e A090206 34 is in the sequence as it is a Fibonacci number and it is composite, the product of 2 and 17. %e A090206 55 is in the sequence as it is a Fibonacci number and it is composite, the product of 5 and 11. %e A090206 89 is not in the sequence because, although it is a Fibonacci number, it is prime. %t A090206 Select[Fibonacci[Range[0, 50]], !PrimeQ[#] &] (* _Vladimir Joseph Stephan Orlovsky_, Jul 22 2008 *) %Y A090206 Cf. A000045, A005478, A050937, A182602. %K A090206 easy,nonn %O A090206 1,4 %A A090206 _Felix Tubiana_, Jan 22 2004