A074252 Number of primes <= n is equal to the sum of squarefree numbers from the smallest prime factor of n to the largest prime factor of n.

1, 4, 12, 30, 84, 9150, 47244, 75360, 177287, 281868, 705790, 3043504, 9669715, 20139930, 32043111, 67447484, 291217662, 7544909388, 8396469108, 21425170627

Offset

0,2

Links

Table of n, a(n) for n=0..19.

Example

pi(84) = 23 and 84 = 2^2*3*7 and 2+3+5+6+7 = 23.

Crossrefs

Cf. A000720.

Sequence in context: A162740 A324943 A301875 * A297079 A074210 A299053

Adjacent sequences: A074249 A074250 A074251 * A074253 A074254 A074255

Keyword

more,nonn

Author

Jason Earls, Sep 20 2002

Extensions

a(6)-a(19) from Donovan Johnson, Oct 12 2008

Status

approved