A145443 In class n of the phi iteration, the number of primes less than the smallest composite number.

1, 2, 2, 2, 2, 1, 3, 1, 1, 2, 0, 0, 0, 1, 0, 1, 3, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 0, 4, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 1, 0, 0, 1, 0, 2, 2, 1, 0, 1, 0, 2, 0, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1, 0, 0, 0, 0, 2, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

Offset: 1

Author

T. D. Noe, Oct 10 2008

Keywords

• nonn

Comments

A number is in class n if n iterations of Euler's phi function produces 2 (see A032358). a(n)>0 for the n in A136040.

Examples

			According to A005239, class 5 begins with 41, 47, 51, 53, 55, 59, 61. There are two primes less than the composite 51. Hence a(5)=2.
		

Links

• T. D. Noe, Table of n, a(n) for n=1..1000
• T. D. Noe, Computing Numbers in Section I of the Totient Iteration

Crossrefs

A098196

Extensions

Modified comment. - T. D. Noe, Nov 18 2008

Extension T. D. Noe, Nov 18 2008