A182564 Number of primes < Fibonacci(n).

0, 0, 0, 0, 1, 2, 4, 5, 8, 11, 16, 23, 34, 50, 74, 111, 166, 250, 376, 574, 871, 1329, 2033, 3120, 4794, 7396, 11425, 17688, 27426, 42612, 66317, 103298, 161207, 251757, 393790, 616645, 966507, 1516410, 2381429, 3743010, 5888201, 9269519, 14604028, 23023555, 36322186, 57337078, 90565070, 143130478

Offset: 0

Author

Alex Ratushnyak, May 05 2012

Keywords

• nonn

Examples

			Fibonacci(7)=13, there are 5 primes less than 13, so a(7)=5.
		

Crossrefs

Cf. A000040, A000045, A006880, A007053, A028505, A038107, A040014.

Programs

Mathematica

Table[If[PrimeQ[Fibonacci[n]],PrimePi[Fibonacci[n]-1],PrimePi[ Fibonacci[ n]]],{n,0,50}] (* Harvey P. Dale, Feb 12 2022 *)

PARI

a(n) = primepi(fibonacci(n)-1) \\ Michel Marcus, May 13 2013