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A205958
a(0) = 1 and a(n) = A180000(n)*a(floor(n/2))^2 for n > 0.
2
1, 1, 1, 1, 2, 2, 3, 3, 48, 16, 40, 40, 270, 270, 945, 63, 129024, 129024, 64512, 64512, 2016000, 96000, 528000, 528000, 144342000, 28868400, 187644600, 20849400, 1787836050, 1787836050, 59594535, 59594535, 3999321544458240, 121191561953280, 1030128276602880
OFFSET
0,5
COMMENTS
lcm(1,2,..,n) = (n!*a(n)) / ((n/2)!*a(n/2))^2.
lcm(1,2,..,n)*a(n) is a divisor of n! and n!/(lcm(1,2,..,n)*a(n)) is a square.
PROG
(Sage)
def A205958(n) :
if n == 0 : return 1
return A180000(n)*A205958(n//2)^2
CROSSREFS
KEYWORD
nonn
AUTHOR
Peter Luschny, Feb 04 2012
STATUS
approved