Search: id:A139590
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%I A139590
%S A139590 8,21,34,55,144,377,2584,4181,6765,17711,46368,75025,121393,196418,
%T A139590 317811,832040,1346269,2178309,5702887,14930352,102334155,165580141,
%U A139590 267914296,701408733,1134903170,4807526976,12586269025,32951280099
%N A139590 Fibonacci numbers with non-Fibonacci number of divisors.
%C A139590 A000005(a(n)) is a non-Fibonacci number A001690.
%e A139590 34 belongs to the sequence because the number of its divisors, 4, is 
               not a Fibonacci number.
%p A139590 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: isA139590 := proc(n) 
               RETURN(isA000045(n) and not isA000045(A000005(n))) ; end: for i from 
               1 to 130 do a000045 := A000045(i) ; if isA139590(a000045) then printf("%d,
               ",a000045) ; fi ; od: - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), 
               May 11 2008
%p A139590 with(combinat): with(numtheory): F:={seq(fibonacci(j),j=1..30)}: a:= 
               proc(n) if member(tau(fibonacci(n)),F) = false then fibonacci(n) 
               else end if end proc: seq(a(n),n=1..50); - Emeric Deutsch (deutsch(AT)duke.poly.edu)
%Y A139590 Cf. A000005, A000045, A001690, A063375, A133021.
%Y A139590 Sequence in context: A003249 A134862 A090206 this_sequence A154894 A000567 
               A124484
%Y A139590 Adjacent sequences: A139587 A139588 A139589 this_sequence A139591 A139592 
               A139593
%K A139590 nonn
%O A139590 1,1
%A A139590 Omar E. Pol (info(AT)polprimos.com), May 09 2008
%E A139590 More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl) and Emeric 
               Deutsch (deutsch(AT)duke.poly.edu), May 11 2008

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