[seqfan] Sum of proper divisors of Fibonacci numbers A139095 A005478

Richard Mathar mathar at strw.leidenuniv.nl
Thu Sep 17 17:36:43 CEST 2009


The sequence
http://research.att.com/~njas/sequences/A139095
shows Fibonacci numbers F which have a sum of proper divisors which is
again a Fibonacci number. So far this contains 1 and the elements
of http://research.att.com/~njas/sequences/A005478 .
It is obvious that all elements of A005478 (prime Fibonacci numbers)
are in A139095 because the only proper divisor of these is 1 which sums to
1, which is a Fibonacci number.

So the question is: is A139095 just the union {1, A005478}?

Richard




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