A153385 Number of primes <= Fibonacci(Fibonacci(n)) = pi(A007570(n)).

0, 0, 0, 0, 1, 3, 8, 51, 1329, 393790, 5670112879

Offset

0,6

Links

Table of n, a(n) for n=0..10.

H. J. Smith, XICalc - Extra Precision Integer Calculator.

Formula

a(n) = pi(Fibonacci(Fibonacci(n)) = A000720(A007570(n)).

Example

a(7) = 51 because Fib(7) = 13, Fib(13) = 233 and there are 51 primes <= 233.

Mathematica

PrimePi@# & /@ (Fibonacci@Fibonacci@# & /@ Range@10) (* Robert G. Wilson v, Feb 17 2009 *)

Prog

(XICalc) Pi(Fib(Fib(n)));
(Magma) [0] cat [#PrimesUpTo(Fibonacci(Fibonacci(n))): n in [1..9]]; // Vincenzo Librandi, Aug 02 2015

Crossrefs

Cf. A000045, A000720, A007570.

Sequence in context: A265961 A019035 A241469 * A026088 A354851 A322461

Adjacent sequences: A153382 A153383 A153384 * A153386 A153387 A153388

Keyword

nonn

Author

Harry J. Smith, Dec 25 2008

Status

approved