|
Search: id:A126854
|
|
|
| A126854 |
|
a(0)=1; for n>0, a(n) = number of earlier terms of the sequence which divide the n-th composite positive integer. |
|
+0
1
|
|
| 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
(list; graph; listen)
|
|
|
OFFSET
|
0,3
|
|
|
LINKS
|
Leroy Quet, Home Page (listed in lieu of email address)
|
|
EXAMPLE
|
The 7th composite is 14. There are three terms from among (a(0),a(1),...a(6)) which 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 (deutsch(AT)duke.poly.edu), 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 (mathar(AT)strw.leidenuniv.nl), Jun 08 2007
|
|
CROSSREFS
|
Sequence in context: A078644 A133700 A087688 this_sequence A115206 A093653 A049982
Adjacent sequences: A126851 A126852 A126853 this_sequence A126855 A126856 A126857
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Leroy Quet May 13 2007
|
|
EXTENSIONS
|
More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu) and R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 27 2007
|
|
|
Search completed in 0.002 seconds
|
