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A217858 Odd part of lcm(1,2,3,...,n). 3
1, 1, 3, 3, 15, 15, 105, 105, 315, 315, 3465, 3465, 45045, 45045, 45045, 45045, 765765, 765765, 14549535, 14549535, 14549535, 14549535, 334639305, 334639305, 1673196525, 1673196525, 5019589575, 5019589575, 145568097675, 145568097675, 4512611027925, 4512611027925, 4512611027925 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
LINKS
FORMULA
a(n) = A000265( A003418(n) ).
a(n) = lcm_{1 <= k <= n, k odd}. - Peter Luschny, Oct 15 2012
a(n) = A025547(floor((n+1)/2)). - Georg Fischer, Nov 29 2022
EXAMPLE
a(8) is the least common multiple of {1,3,5,7}.
MAPLE
A217858 := n -> ilcm(op(select(j->j mod 2 = 1, [$1..n]))):
seq(A217858(i), i = 1..33); # Peter Luschny, Oct 15 2012
MATHEMATICA
a[n_] := LCM @@ Select[Range[n], OddQ]; Array[a, 33] (* Jean-François Alcover, Jun 27 2019 *)
PROG
(PARI)
A003418(n) = lcm(vector(n, k, k));
A000265(n) = n/2^valuation(n, 2);
a(n) = A000265( A003418(n) );
(Sage)
def A217858(n): return lcm([j for j in (1..n) if is_odd(j)])
[A217858(n) for n in (1..33)] # Peter Luschny, Oct 15 2012
CROSSREFS
Sequence in context: A362531 A129356 A290344 * A185275 A055634 A133221
KEYWORD
nonn
AUTHOR
Joerg Arndt, Oct 13 2012
STATUS
approved

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Last modified July 21 04:02 EDT 2024. Contains 374463 sequences. (Running on oeis4.)