OFFSET
1,2
LINKS
Chai Wah Wu, Table of n, a(n) for n = 1..500
FORMULA
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
(PARI) a(n) = my(f = factor(prod(i = 0, (n-1)\2, n - 2*i))); prod(i = 1, #f~, f[i, 1]^(f[i, 2] % 3)); \\ Amiram Eldar, Sep 07 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Artur Jasinski, Oct 15 2008
STATUS
approved