2,2

This is a good approximation to pi(n), the number of prime numbers<=n.

Table of n, a(n) for n=2..72.

Eric Weisstein's World of Mathematics, More information

Cf. A000720, A047784, A052434.

Sequence in context: A054846 A084520 A084510 * A283302 A225593 A057360

Adjacent sequences: A053617 A053618 A053619 * A053621 A053622 A053623

nonn

Henry Bottomley, Mar 21 2000

approved