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A139095 Fibonacci numbers whose sum of proper divisors is also a Fibonacci number. 2
1, 1, 2, 3, 5, 13, 89, 233, 1597, 28657, 514229, 433494437, 2971215073, 99194853094755497, 1066340417491710595814572169, 19134702400093278081449423917 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Numbers n such that A001065(n) is a Fibonacci number.

Comment from R. J. Mathar, Sep 17 2009: Certainly this contains 1 and the terms of A005478. Does it contain any other terms?

A001065(a(n)) is a Fibonacci number.

LINKS

Table of n, a(n) for n=1..16.

MAPLE

isA000045 := proc(n) local i, f ; for i from 0 do f := combinat[fibonacci](i) ; if f = n then RETURN(true) ; elif f > n then RETURN(false) ; fi ; od; end: A001065 := proc(n) numtheory[sigma](n)-n ; end: isA139095 := proc(n) RETURN( isA000045(n) and isA000045(A001065(n)) ) ; end: for i from 1 to 230 do if isA139095(combinat[fibonacci](i)) then printf("%d, ", combinat[fibonacci](i)) ; fi ; od: # R. J. Mathar, May 22 2008

CROSSREFS

Cf. A000045, A001065, A139589, A005478.

Sequence in context: A074691 A139589 A152114 * A005478 A117740 A041047

Adjacent sequences:  A139092 A139093 A139094 * A139096 A139097 A139098

KEYWORD

more,nonn

AUTHOR

Omar E. Pol, May 11 2008

EXTENSIONS

More terms from R. J. Mathar, May 22 2008

STATUS

approved

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Last modified March 26 00:51 EDT 2017. Contains 284111 sequences.