

A071824


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


0



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
(list;
graph;
refs;
listen;
history;
text;
internal format)



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: A025778 A294622 A078451 * A224921 A225370 A114540
Adjacent sequences: A071821 A071822 A071823 * A071825 A071826 A071827


KEYWORD

easy,nonn


AUTHOR

Benoit Cloitre, Jun 07 2002


STATUS

approved



