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 A114306 Numbers k such that Fibonacci(k) has more divisors than k does. 1

%I

%S 9,12,15,16,18,19,20,21,24,25,27,28,30,31,32,33,35,36,37,38,39,40,41,

%T 42,44,45,46,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,

%U 67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,84,85,86,87,88,89,90,91

%N Numbers k such that Fibonacci(k) has more divisors than k does.

%H Amiram Eldar, <a href="/A114306/b114306.txt">Table of n, a(n) for n = 1..1377</a> (terms 1..500 from Jinyuan Wang)

%e 15 is in the sequence because 610 (= Fibonacci(15)) has more divisors than 15.

%p with(combinat): with(numtheory): b:=proc(n) if tau(fibonacci(n))>tau(n) then n else fi end: seq(b(n),n=1..100); # _Emeric Deutsch_, May 13 2006

%t Select[Range[1, 100], DivisorSigma[0, Fibonacci[#]] > DivisorSigma[0, #] &] (* _Vaclav Kotesovec_, Feb 13 2019 *)

%o (PARI) isok(n) = numdiv(fibonacci(n)) > numdiv(n); \\ _Michel Marcus_, Feb 13 2019

%Y Cf. A000005, A000045, A063375.

%K nonn

%O 1,1

%A _Shyam Sunder Gupta_, Feb 05 2006

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Last modified April 11 09:54 EDT 2021. Contains 342886 sequences. (Running on oeis4.)