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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

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Last modified April 14 05:00 EDT 2021. Contains 342941 sequences. (Running on oeis4.)