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%I #16 Nov 17 2018 12:02:35
%S 4,1,5,3,4,7,11,9,10,19,29,24,53,11,32,43,25,34,59,31,45,38,83,11,47,
%T 29,38,67,35,51,43,47,45,46,13,59,36,19,11,15,13,14,9,23,16,13,29,21,
%U 25,23,24,47,71,59,65,62,127,63,95,79,87,83,85,84,13,97,55,76,131,69,100,13,113
%N Conway's subprime Fibonacci sequence starting with (4,1).
%C Similar to the Fibonacci recursion starting with (4, 1), but each new nonprime term is divided by its least prime factor. Sequence enters a loop of length 136 after 8 terms on reaching (11, 9).
%H Wouter Meeussen, <a href="/A214892/b214892.txt">Table of n, a(n) for n = 1..144</a>
%H Richard K. Guy, Tanya Khovanova and Julian Salazar, <a href="http://arxiv.org/abs/1207.5099">Conway's subprime Fibonacci sequences</a>, arXiv:1207.5099 [math.NT], 2012-2014.
%t (* see A214674 *)
%t a[1] = 4; a[2] = 1; a[n_] := a[n] = If[an = a[n-2]+a[n-1]; PrimeQ[an], an, an/FactorInteger[an][[1, 1]]]; Array[a, 80] (* _Jean-François Alcover_, Nov 17 2018 *)
%Y Cf. A000045, A020639, A175723, A214551, A014682, A214674, A214892-A214898.
%K nonn
%O 1,1
%A _Wouter Meeussen_, Jul 29 2012