cp's OEIS Frontend

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.

A061305 Squarefree Fibonacci numbers.

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%I A061305 #39 Oct 27 2023 22:05:37
%S A061305 1,1,2,3,5,13,21,34,55,89,233,377,610,987,1597,4181,6765,10946,17711,
%T A061305 28657,121393,196418,317811,514229,1346269,2178309,3524578,5702887,
%U A061305 9227465,24157817,39088169,63245986,102334155,165580141,433494437,701408733,1134903170,1836311903
%N A061305 Squarefree Fibonacci numbers.
%C A061305 Union of A074691 and A075735. - _R. J. Mathar_, Feb 06 2010
%C A061305 About 60% of entries are of the form 4k+1; 20% are of the form 4k+2; 20% are of the form 4k+3. Obviously no term is divisible by 4. - _Carmine Suriano_, Feb 27 2014
%C A061305 Contains A030426 as a subsequence unless there exist Wall-Sun-Sun primes. - _Max Alekseyev_, Jan 04 2018
%H A061305 Amiram Eldar, <a href="/A061305/b061305.txt">Table of n, a(n) for n = 1..1080</a> (terms 1..200 from Zak Seidov)
%F A061305 Set difference of A000045 and A061899. a(n) = A000045(A037918(n)). - _R. J. Mathar_, Feb 16 2010
%e A061305 55 = 5 * 11 is a squarefree Fibonacci number.
%t A061305 a={}; Do[f=Fibonacci[n]; If[SquareFreeQ[f], AppendTo[a, f]], {n, 1, 50}]; a (* _Vladimir Joseph Stephan Orlovsky_, Jul 22 2008 *)
%t A061305 Select[Fibonacci[Range[50]],SquareFreeQ] (* _Harvey P. Dale_, Aug 26 2021 *)
%o A061305 (PARI) { n=0; g=0; f=1; for (i=1, 500, if (issquarefree(g), write("b061305.txt", n++, " ", g)); if (n==200, break); s=f; f+=g; g=s ) } \\ _Harry J. Smith_, Jul 21 2009
%Y A061305 Intersection of A000045 and A005117.
%K A061305 nonn,easy
%O A061305 1,3
%A A061305 _Amarnath Murthy_, Apr 26 2001
%E A061305 More terms from _Asher Auel_, May 14 2001
%E A061305 Mathematica updated by _Jean-François Alcover_, Jul 04 2013