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A071824
Number of x with largest prime factor of the form 4k+1 less than or equal to n.
1
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
OFFSET
1,10
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) )
PROG
(PARI) a(n)=sum(i=2, n, (factor(i)[omega(i), 1])-1)%4==0)
CROSSREFS
Sequence in context: A078451 A332247 A341168 * A224921 A225370 A114540
KEYWORD
easy,nonn
AUTHOR
Benoit Cloitre, Jun 07 2002
EXTENSIONS
Missing a(1)=0 inserted by Sean A. Irvine, Aug 15 2024
STATUS
approved