1,1

What is the asymptotic behavior of this sequence?

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

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

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

(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

Cf. A000045, A001065, A272412.

Sequence in context: A308529 A320098 A320968 * A242261 A189892 A240877

Adjacent sequences: A279356 A279357 A279358 * A279360 A279361 A279362

nonn,more

Altug Alkan, Dec 16 2016

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

approved