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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

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Last modified April 26 03:37 EDT 2019. Contains 322469 sequences. (Running on oeis4.)