|
|
A085501
|
|
Number of prime powers p^k <= n that are not prime (k = 0 or k > 1).
|
|
6
|
|
|
1, 1, 1, 2, 2, 2, 2, 3, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 11, 11
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,4
|
|
COMMENTS
|
for n<36=(2*3)^2: a(n) = A069623(n).
|
|
LINKS
|
|
|
PROG
|
(PARI) first(n)=my(v=vector(n), s=1); for(e=2, logint(n, 2), forprime(p=2, sqrtnint(n, e), v[p^e]=1)); for(i=1, n, s+=v[i]; v[i]=s); v \\ Charles R Greathouse IV, Jul 21 2017
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|