

A238329


Fibonacci numbers that have no prime factors of the form 4k+1.


0



1, 1, 2, 3, 8, 21, 144, 987, 46368, 2178309, 4807526976
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OFFSET

1,3


COMMENTS

These are Fibonacci numbers of order 1, 2, 3, 4, 6, 8, 12, 16, 24, 32, and 48. It is somewhat surprising that these are only these Fibonacci numbers having this property.


LINKS



MATHEMATICA

Join[{1, 1}, Select[Fibonacci[Range[200]], Union[Mod[Transpose[FactorInteger[#]][[1]], 4]][[1]] > 1 &]]
npfQ[n_]:=Count[FactorInteger[n][[All, 1]], _?(Mod[#, 4]==1&)]==0; Join[ {1, 1}, Select[ Fibonacci[Range[50]], npfQ]] (* Harvey P. Dale, Jun 15 2019 *)


CROSSREFS



KEYWORD

nonn,fini,full


AUTHOR



STATUS

approved



