Number of steps in Eratosthenes' sieve for n! is A133228(n).
Number of primes less than 5! is equal = 120-59-19-7-4-1 = 30 = A003604(5).
Table of n, a(n) for n=1..4.
a(1)=59 because in first step we removed all numbers divisible by 2 (=60) with exception first one number 2.
a(2)=19 because number of numbers divisible by 3 and not divisible by 2 is 20 and we remove all with exception first one number 3.
A003604, A133228, A145532-A145540
Sequence in context: A088665 A198378 A159250 * A152214 A033379 A122252
Adjacent sequences: A145529 A145530 A145531 * A145533 A145534 A145535
Artur Jasinski, Oct 12 2008