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A279359 Even numbers n such that sum of proper divisors of n is a Fibonacci number. 0
2, 4, 10, 18, 36, 62, 90, 902, 1214, 2936, 3436, 325726, 378646, 646840, 5432174, 273222344, 285775216, 1411668430, 1416411790, 2586905784 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

What is the asymptotic behavior of this sequence?

No more terms below 10^10. - Amiram Eldar, Oct 18 2019

LINKS

Table of n, a(n) for n=1..20.

EXAMPLE

18 is a term because 1 + 2 + 3 + 6 + 9 = 21 is a Fibonacci number.

PROG

(PARI) isFibonacci(n)=my(k=n^2); issquare(k+=(k+1)<<2) || (n>0 && issquare(k-8));

is(n)=isFibonacci(sigma(n)-n)&&n%2==0

CROSSREFS

Cf. A000045, A001065, A272412.

Sequence in context: A308529 A320098 A320968 * A242261 A189892 A240877

Adjacent sequences:  A279356 A279357 A279358 * A279360 A279361 A279362

KEYWORD

nonn,more

AUTHOR

Altug Alkan, Dec 16 2016

EXTENSIONS

a(18)-a(20) from Amiram Eldar, Oct 18 2019

STATUS

approved

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Last modified September 25 20:01 EDT 2020. Contains 337344 sequences. (Running on oeis4.)