A071824 Number of x with largest prime factor of the form 4k+1 less than or equal to n.

0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 3, 3, 4, 4, 5, 5, 5, 6, 6, 6, 6, 6, 7, 8, 8, 8, 9, 10, 10, 10, 10, 11, 11, 11, 12, 12, 13, 14, 15, 15, 15, 15, 16, 16, 16, 16, 16, 17, 18, 19, 20, 20, 20, 20, 20, 21, 21, 22, 23, 23, 23, 23, 24, 24, 24, 25, 25, 25, 25, 25, 26, 27, 28, 28, 28, 29, 29

Offset

1,9

Comments

Conjecture : for n > 1000 a(n) - n/2 < - sqrt(n) ( if b(n) denotes the number of x with largest prime factor of the form 4k+3 less than or equal to n, it is conjectured that if n > 1000 b(n)- n/2 > sqrt(n) )

Links

Table of n, a(n) for n=1..78.

Prog

(PARI) for(n=2, 200, print1(sum(i=2, n, if((component(component(factor(i), 1), omega(i))-1)%4, 0, 1)), ", "))

Crossrefs

Sequence in context: A078451 A332247 A341168 * A224921 A225370 A114540

Adjacent sequences: A071821 A071822 A071823 * A071825 A071826 A071827

Keyword

easy,nonn

Author

Benoit Cloitre, Jun 07 2002

Status

approved