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%I #19 Oct 16 2019 01:28:10
%S 1,1,2,3,5,13,89,233,610,987,1597,10946,28657,514229,3524578,9227465,
%T 24157817,39088169,63245986,433494437,1836311903,2971215073,
%U 7778742049,20365011074,591286729879,4052739537881,17167680177565,44945570212853
%N Fibonacci numbers with Fibonacci number of divisors.
%C A000005(a(n)) is a Fibonacci number.
%C For the terms shown here (in the Data section) the number of divisors is 1 or 2 or 8. - _Emeric Deutsch_, May 12 2008
%C Up to n = 104 the number of divisors is still 1, 2 or 8. - _Amiram Eldar_, Oct 15 2019
%H Amiram Eldar, <a href="/A139589/b139589.txt">Table of n, a(n) for n = 1..104</a>
%p A000045 := proc(n) option remember ; coeftayl( x/(1-x-x^2),x=0,n) ; end: isA000045 := proc(n) local a; for a from 0 do if A000045(a) > n then RETURN(false) ; elif A000045(a)=n then RETURN(true) ; fi ; od: end: A000005 := proc(n) numtheory[tau](n) ; end: isA139589 := proc(n) RETURN(isA000045(n) and isA000045(A000005(n))) ; end: for i from 1 to 130 do a000045 := A000045(i) ; if isA139589(a000045) then printf("%d,",a000045) ; fi ; od: # _R. J. Mathar_, May 11 2008
%p with(combinat): with(numtheory): F:={seq(fibonacci(k),k=1..100)}: a:=proc(n) if member(tau(fibonacci(n)),F)=true then fibonacci(n) else end if end proc: seq(a(n),n=1..70); # _Emeric Deutsch_, May 12 2008
%t With[{s = Array[Fibonacci, 80]}, Select[s, ! FreeQ[s, DivisorSigma[0, #]] &]] (* _Michael De Vlieger_, Oct 15 2019 *)
%Y Cf. A000005, A000045, A063375, A133021.
%K nonn
%O 1,3
%A _Omar E. Pol_, May 09 2008
%E More terms from _R. J. Mathar_ and _Emeric Deutsch_, May 11 2008
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