|
|
A063035
|
|
Number of integers m <= 10^n that contain a square factor (i.e., belong to A013929).
|
|
4
|
|
|
3, 39, 392, 3917, 39206, 392074, 3920709, 39207306, 392072876, 3920729058, 39207289720, 392072897726, 3920728981706, 39207289814053, 392072898145897, 3920728981459595
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
Note that "containing a square factor" (A013929) is different from "squareful" (A001694).
|
|
LINKS
|
|
|
FORMULA
|
|
|
MATHEMATICA
|
f[n_] := Sum[-MoebiusMu[i]Floor[n/i^2], {i, 2, Sqrt@ n}]; Table[ f[10^n], {n, 0, 14}]
|
|
PROG
|
(PARI) { default(realprecision, 50); for (n=1, 100, t=10^n - 1; a=10^n - sum(k=1, sqrt(t), moebius(k)*floor(t/k^2)); write("b063035.txt", n, " ", a) ) } \\ Harry J. Smith, Aug 16 2009
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
Edited (with a more precise definition and a new value for a(1)) by N. J. A. Sloane, Aug 06 2012. As a result of this change, the programs probably now give the wrong value for a(1). The source of the trouble was the ambiguous meaning of squareful - the official definition of squareful is A001694.
|
|
STATUS
|
approved
|
|
|
|