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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 Table of n, a(n) for n=1..33. 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 Cf. A003418, A025547, A128501, A216917. Sequence in context: A362531 A129356 A290344 * A185275 A055634 A133221 Adjacent sequences: A217855 A217856 A217857 * A217859 A217860 A217861 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.)