A126854 a(0)=1; for n>0, a(n) = number of earlier terms of the sequence that divide the n-th composite positive integer.

1, 1, 2, 3, 3, 3, 6, 3, 6, 3, 10, 4, 7, 3, 12, 2, 4, 8, 7, 13, 7, 8, 4, 5, 16, 4, 9, 12, 15, 8, 11, 4, 23, 5, 7, 8, 10, 13, 5, 17, 8, 4, 26, 4, 13, 17, 8, 13, 13, 9, 13, 29, 4, 12, 12, 7, 19, 24, 10, 4, 30, 7, 4, 9, 21, 23, 14, 16, 8, 4, 6, 38, 11, 13, 21, 15, 30, 21, 4, 32, 12, 8, 33, 15, 7, 17

Offset

0,3

Links

Table of n, a(n) for n=0..85.

Example

The 7th composite is 14. There are three terms from among (a(0),a(1),...a(6)) that divide 14 (a(0)=1, a(1)=1, a(2)=2). So a(7) = 3.

Maple

c:=proc(n) if isprime(n)=false then n else fi end: C:=[seq(c(n), n=2..200)]: a[0]:=1: for n from 1 to 110 do a[n]:=0: for j from 0 to n-1 do if C[n] mod a[j] = 0 then a[n]:=a[n]+1 else fi od: od: seq(a[n], n=0..110); # Emeric Deutsch, May 27 2007
A002805 := proc(n) option remember ; local a; if n = 1 then 4 ; else a := 1+A002805(n-1) ; while isprime(a) do a := a+1 ; od ; RETURN(a) ; fi ; end: A126854 := proc(nmax) local a, anext, n, acomp, i; a := [1] ; while nops(a) < nmax do n := nops(a) ; anext := 0 ; acomp := A002805(n) ; for i from 1 to n do if acomp mod op(i, a) = 0 then anext := anext+1 ; fi ; od ; a := [op(a), anext] ; od ; a ; end: A126854(100) ; # R. J. Mathar, Jun 08 2007

Crossrefs

Sequence in context: A078644 A133700 A087688 * A115206 A093653 A205442

Adjacent sequences: A126851 A126852 A126853 * A126855 A126856 A126857

Keyword

nonn

Author

Leroy Quet, May 13 2007

Extensions

More terms from Emeric Deutsch and R. J. Mathar, May 27 2007

Status

approved