login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A295084 Number of sqrt(n)-smooth numbers <= n. 9
1, 1, 1, 3, 3, 3, 3, 4, 7, 7, 7, 8, 8, 8, 8, 9, 9, 10, 10, 10, 10, 10, 10, 11, 16, 16, 17, 17, 17, 18, 18, 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 21, 22, 22, 22, 23, 30, 31, 31, 31, 31, 32, 32, 33, 33, 33, 33, 34, 34, 34, 35, 36, 36, 36, 36, 36, 36, 37, 37, 38, 38, 38, 39, 39, 39, 39, 39, 40 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,4
COMMENTS
a(n) = number of positive integers m<=n such that A006530(m) <= sqrt(n).
LINKS
Wikipedia, Smooth number
FORMULA
a(n) = n - A241419(n).
If n is in A063539, then a(n)=a(n-1)+1; if n is in A001248, i.e., n=p^2 for prime p, then a(n)=a(n-1)+p; otherwise a(n)=a(n-1).
a(n) = (1 - log(2))*n + O(n/log(n)) as n -> infinity. - Robert Israel, Nov 14 2017
MAPLE
N:= 100: # to get a(1)..a(N)
G:= [0, seq(max(numtheory:-factorset(n)), n=2..N)]:
seq(nops(select(t -> t^2 <= n, G[1..n])), n=1..N); # Robert Israel, Nov 14 2017
a:=[];
for n from 1 to 100 do
c:=0;
for m from 1 to n do
if A006530(m)^2 <= n then c:=c+1; fi; od:
a:=[op(a), c];
od:
a; # (Included because variants of it will apply to related sequences) - N. J. A. Sloane, Apr 10 2020
PROG
(PARI) A295084(n) = my(r=n); forprime(p=sqrtint(n)+1, n, r-=n\p); r;
CROSSREFS
Cf. A048098 (indices of records), A063539, A241419.
The following are all different versions of sqrt(n)-smooth numbers: A048098, A063539, A064775, A295084, A333535, A333536.
Sequence in context: A006671 A046074 A328914 * A068048 A176994 A264050
KEYWORD
nonn,look
AUTHOR
Max Alekseyev, Nov 13 2017
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 13:25 EDT 2024. Contains 371254 sequences. (Running on oeis4.)