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 A073958 #14 Nov 21 2013 12:47:51 %S A073958 1,2,3,5,8,13,21,34,55,89,233,377,610,987,1597,2584,4181,10946,17711, %T A073958 28657,75025,121393,514229,1346269,3524578,5702887,9227465,24157817, %U A073958 39088169,63245986,165580141,433494437 %N A073958 Fibonacci numbers for which the number of prime factors (with multiplicity) is a Fibonacci number. %C A073958 The prime Fibonacci numbers, A005478, are a subsequence. %H A073958 Charles R Greathouse IV, <a href="/A073958/b073958.txt">Table of n, a(n) for n = 1..328</a> %e A073958 Example: 8=2*2*2, the number of prime factors is equal to 3, a Fibonacci number. %t A073958 With[{fibs=Fibonacci[Range[0,50]]},Rest[Select[fibs,MemberQ[fibs, PrimeOmega[#]]&]]] (* _Harvey P. Dale_, Oct 27 2011 *) %o A073958 (PARI) isFibonacci(n)=my(k=n^2);k+=((k + 1) << 2);issquare(k) || (n > 0 && issquare(k-8)) %o A073958 select(n->isFibonacci(bigomega(n)), vector(99,i,fibonacci(i+1))) \\ _Charles R Greathouse IV_, Jun 17 2013 %Y A073958 Cf. A000045. %K A073958 nice,nonn %O A073958 1,2 %A A073958 _Felice Russo_, Sep 03 2002