OFFSET
1,7
COMMENTS
For n>1, a(n)=1 corresponds to numbers n that are odd primes.
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..5000
MAPLE
issquarefree := proc(n::integer) local nf, ifa ; nf := op(2, ifactors(n)) ; for ifa from 1 to nops(nf) do if op(2, op(ifa, nf)) >= 2 then RETURN(false) ; fi ; od : RETURN(true) ; end: A001221 := proc(n::integer) RETURN(nops(numtheory[factorset](n))) ; end: A056911 := proc(maxn) local n, a ; a := [1] ; for n from 3 to maxn by 2 do if issquarefree(n) then a := [op(a), n] ; fi ; od : RETURN(a) ; end: A120675 := proc(maxn) local a, n; a := A056911(maxn) ; for n from 1 to nops(a) do a := subsop(n=A001221(a[n]), a) ; od ; RETURN(a) ; end: nmax := 600 : a := A120675(nmax) : for n from 1 to nops(a) do printf("%d, ", a[n]) ; od ; amer% # R. J. Mathar, Aug 17 2006
MATHEMATICA
PrimeNu[Select[Range[1, 1000, 2], SquareFreeQ]] (* G. C. Greubel, May 11 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Lekraj Beedassy, Jun 24 2006
EXTENSIONS
Corrected and extended by R. J. Mathar, Aug 17 2006
STATUS
approved