A366368 -id:A366368 - cp's OEIS frontend

A139550 a(n) = lcm(1..floor(n/2)).

1, 1, 1, 1, 2, 2, 6, 6, 12, 12, 60, 60, 60, 60, 420, 420, 840, 840, 2520, 2520, 2520, 2520, 27720, 27720, 27720, 27720, 360360, 360360, 360360, 360360, 360360, 360360, 720720, 720720, 12252240, 12252240, 12252240, 12252240, 232792560, 232792560

Offset: 0

Mats Granvik, Apr 27 2008

nonn

Row products of A139549.

Cf. A139549, A003418, A366368, A366369.

LCM := proc (n) local i; ilcm(seq(i,i=1..n)) end; A139550 := n -> LCM(n/2); seq(A139550(n),n=0..40); # Peter Luschny, Jun 09 2011

Join[{1,1},Table[LCM@@Range[Floor[n/2]],{n,2,40}]] (* Harvey P. Dale, Jan 12 2024 *)

a(n) = A003418(floor(n/2)) = A366368(n) / A003418(n) = A003418(n) / A366369(n). - Max Alekseyev, Oct 08 2023

Offset corrected by Peter Luschny, Jun 09 2011

A366369 a(n) = product of primes p such that p^k <= n < 2*p^k for some k >= 1.

Original entry on oeis.org

1, 1, 2, 6, 6, 30, 10, 70, 70, 210, 42, 462, 462, 6006, 858, 858, 858, 14586, 4862, 92378, 92378, 92378, 8398, 193154, 193154, 965770, 74290, 222870, 222870, 6463230, 6463230, 200360130, 200360130, 200360130, 11785890, 11785890, 11785890, 436077930, 22951470, 22951470, 22951470, 941010270, 941010270

Offset: 0

Max Alekseyev, Oct 08 2023

nonn

Subsequence of A005117.

Cf. A003418, A139550, A366368.

a366369(n) = my(r=1); forprime(p=2, n, if(n<2*p^logint(n,p), r*=p)); r;

a(n) = A003418(n) / A139550(n) = A003418(n) / A003418(floor(n/2)).

a(n) = A003418(n)^2 / A366368(n).

cp's OEIS Frontend

A139550 a(n) = lcm(1..floor(n/2)).

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