A325627 a(n) is the largest prime factor in A030426(n).

2, 5, 13, 89, 233, 1597, 113, 28657, 514229, 2417, 2221, 59369, 433494437, 2971215073, 55945741, 2710260697, 555003497, 1429913, 46165371073, 86020717, 92180471494753, 99194853094755497, 1665088321800481, 361040209, 770857978613, 512119709, 8242065050061761

Offset: 1

Author

Vincenzo Librandi, May 13 2019

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..222
• C. L. Stewart, On Divisors of Fermat, Fibonacci, Lucas, and Lehmer Numbers, Proceedings of the London Mathematical Society, Vol. s3-35, No. 3 (1977), pp. 425-447. See p. 430.

Crossrefs

Cf. A000045, A005478, A006530, A030426, A060385, A325626.

Programs

Magma

[Maximum(PrimeDivisors(Fibonacci(NthPrime(n)))): n in [2..35]];

Mathematica

Table[FactorInteger[Fibonacci [Prime[n]]][[-1, 1]], {n, 2, 30}]

Formula

From Amiram Eldar, Oct 25 2024: (Start)

a(n) = A006530(A030426(n)).

a(n) = A060385(prime(n+1)).

a(n) > c * prime(n) * log(prime(n)), where c is an effectively computable positive constant (Stewart, 1977). (End)