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A141864 Frequency of A038511 in the interval [(n-1)*3*5*7,n*3*5*7]. 1
1, 5, 5, 8, 6, 9, 8, 8, 10, 8, 9, 10, 11, 10, 8, 9, 11, 10, 13, 8, 13, 9, 9, 14, 11, 7, 11, 11, 12, 14, 11, 10, 12, 10, 10, 11, 12, 12, 10, 14, 8, 14, 12, 13, 10, 12, 14, 8, 14, 12, 13, 11, 11, 11, 14, 7, 16, 12, 14, 9, 9, 16, 12, 11, 14, 11, 10, 14, 12, 14, 17, 8, 12, 10, 15, 12, 15, 12 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

A value of A038511(0)=1 is artificially introduced which leads to a(1)=1 by definition.

LINKS

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

EXAMPLE

In the 2nd interval from 105 to 210 we find A038511(1)=121, A038511(2)=143, A038511(3)=169,

A038511(4)=187 and A038511(5)=209, that is a(2)=5 entries.

In the 3rd interval from 210 to 315 we find A038511(6)=221, A038511(7)=247, A038511(8)=253,

A038511(9)=289 and A038511(10)=299, that is a(3)=5 entries.

MAPLE

isA038511 := proc(n) local pfs; if isprime(n) then false; else pfs := numtheory[factorset](n) ; RETURN( pfs intersect {2, 3, 5, 7} = {}) ; fi; end:

A141864 := proc(n) local k, a ; if n = 1 then 1; else a := 0 ; for k from (n-1)*105 to n*105 do if isA038511(k) then a := a+1 ; fi; od: a; fi; end:

seq(A141864(n), n=1..90) ; # R. J. Mathar, Aug 03 2009

CROSSREFS

Cf. A002808, A141468, A038511.

Sequence in context: A102729 A021183 A193424 * A245189 A217169 A141538

Adjacent sequences:  A141861 A141862 A141863 * A141865 A141866 A141867

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Sep 15 2008

EXTENSIONS

Edited, a(13) corrected by R. J. Mathar, Aug 03 2009

STATUS

approved

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Last modified June 7 02:48 EDT 2020. Contains 334836 sequences. (Running on oeis4.)