|
| |
|
|
A145643
|
|
Cubefree part of n!!.
|
|
2
|
|
|
|
1, 2, 3, 1, 15, 6, 105, 6, 35, 60, 385, 90, 5005, 1260, 75075, 315, 1276275, 210, 24249225, 525, 509233725, 11550, 11712375675, 34650, 2342475135, 900900, 2342475135, 3153150, 67931778915, 28028, 2105885146365, 14014, 2573859623335
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,2
|
|
|
LINKS
|
Chai Wah Wu, Table of n, a(n) for n = 1..500
|
|
|
FORMULA
|
a(n) = A050985(A006882(n)). - Michel Marcus, May 11 2020
|
|
|
MATHEMATICA
|
CubefreePart[n_Integer?Positive] := Times @@ Power @@@ ({#[[1]], Mod[ #[[2]], 3]} & /@ FactorInteger[n]); Table[CubefreePart[n!! ], {n, 1, 40}]
|
|
|
PROG
|
(Python)
from sympy import factorint, prod
def A145643(n):
return 1 if n <= 1 else prod(p**(e % 3) for p, e in factorint(prod(range(n, 0, -2))).items())
# Chai Wah Wu, Feb 04 2015
|
|
|
CROSSREFS
|
Cf. A004709, A050985, A006882, A069705 (cubefree part of 2^n), A145642.
Sequence in context: A102583 A030780 A193683 * A338208 A323155 A145142
Adjacent sequences: A145640 A145641 A145642 * A145644 A145645 A145646
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
Artur Jasinski, Oct 15 2008
|
|
|
STATUS
|
approved
|
| |
|
|
