A301561 Sphenic Fibonacci numbers.

610, 987, 10946, 3524578, 9227465, 24157817, 39088169, 63245986, 1836311903, 7778742049, 20365011074, 591286729879, 4052739537881, 17167680177565, 44945570212853, 61305790721611591, 420196140727489673, 1500520536206896083277, 6356306993006846248183

Offset: 1

Author

Waldemar Puszkarz, Mar 23 2018

Keywords

• nonn

Comments

Intersection of A000045 and A007304. There are 28 sphenic numbers among the first 200 positive Fibonacci numbers.

Examples

			610 is a term since it is a Fibonacci number that is a product of 3 distinct primes, 610=2*5*61, which makes it a sphenic number.
		

Crossrefs

Cf. A000045, A007304, A061305 (squarefree Fibonaccis), A137563 (Fibonaccis with 3 distinct primes).

Programs

Mathematica

Select[Fibonacci@Range[120], SquareFreeQ[#]&&PrimeNu[#]==3&]

PARI

for(n=1, 120, fn=fibonacci(n); issquarefree(fn)&&omega(fn)==3&&print1(fn ","))

Formula

A000045 INTERSECT A007304.