A135954 Nonprime Fibonacci numbers with prime indices (A050937) that have exactly 3 prime factors.

24157817, 44945570212853, 1500520536206896083277, 50095301248058391139327916261, 11463113765491467695340528626429782121, 30010821454963453907530667147829489881, 2211236406303914545699412969744873993387956988653, 103881042195729914708510518382775401680142036775841

Offset

1,1

Comments

Conjecture: All numbers in this sequence are products of three sums of two squares.

Links

Table of n, a(n) for n=1..8.

Mathematica

k = {}; Do[If[ !PrimeQ[Fibonacci[Prime[n]]], c = Length[FactorInteger[Fibonacci[Prime[n]]]]; If[c == 3, AppendTo[k, Fibonacci[Prime[n]]]]], {n, 1, 50}]; k

Prog

(PARI) f(n) = forprime(x=2, n, p=fibonacci(x); if(!isprime(p) && omega(p) == 3, print1(p", "))) \\ Georg Fischer, Feb 15 2025

Crossrefs

Cf. A000045, A001605, A050937, A075737, A090819, A134787, A134851, A134852, A135953, A135955, A135956, A135957.

Sequence in context: A104922 A058323 A251248 * A203260 A268290 A183791

Adjacent sequences: A135951 A135952 A135953 * A135955 A135956 A135957

Keyword

nonn

Author

Artur Jasinski, Dec 08 2007

Extensions

a(6)-a(8) from Georg Fischer, Feb 15 2025

Status

approved