login
A263468
Fibonacci primes equal to a sum of squares of two Fibonacci numbers at least one of which is also prime.
1
5, 13, 89, 233, 28657, 2971215073
OFFSET
1,1
COMMENTS
Same as Fibonacci numbers F(2k+1) such that at least two of the numbers F(2k+1), F(k), F(k+1) are prime (because F(2k+1) = F(k)^2 + F(k+1)^2 and F(a*b)= F(a) * F(b))). Thus the two squares are of consecutive Fibonacci numbers.
No other terms up to F(2904353).
The corresponding Fibonacci indices are in A263467.
Subsequence of A002144 and A002313.
FORMULA
a(n) = A000045(A263467(n)).
EXAMPLE
F(47) = 2971215073 = 28657^2 + 46368^2 = F(23)^2 + F(24)^2 and 2971215073 and 28657 are prime, so 2971215073 is a member.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Jonathan Sondow, Nov 04 2015
STATUS
approved