|
Search: id:A139095
|
|
|
| A139095 |
|
Fibonacci numbers whose sum of proper divisors is also a Fibonacci number. |
|
+0
3
|
|
| 1, 1, 2, 3, 5, 13, 89, 233, 1597, 28657, 514229, 433494437, 2971215073, 99194853094755497, 1066340417491710595814572169, 19134702400093278081449423917
(list; graph; listen)
|
|
|
OFFSET
|
1,3
|
|
|
COMMENT
|
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.
|
|
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 (mathar(AT)strw.leidenuniv.nl), May 22 2008
|
|
CROSSREFS
|
Cf. A000045, A001065, A139589, A005478.
Sequence in context: A074691 A139589 A152114 this_sequence A005478 A117740 A041047
Adjacent sequences: A139092 A139093 A139094 this_sequence A139096 A139097 A139098
|
|
KEYWORD
|
more,nonn
|
|
AUTHOR
|
Omar E. Pol (info(AT)polprimos.com), May 11 2008
|
|
EXTENSIONS
|
More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 22 2008
|
|
|
Search completed in 0.002 seconds
|
