cp's OEIS Frontend

A109849 a(1) = 1, a(2) = 2; a(n) = lcm(n, a(n-2)), a(n+1) = lcm((n+1), a(n-3)) and so on until a(2n-1) = lcm(2n-1, a(1)). Then a(2n) = lcm(2n, a(2n-2)) and so on.

%I A109849 #12 Mar 07 2018 06:47:44
%S A109849 1,2,3,4,5,12,21,8,9,40,231,12,65,28,15,16,17,144,285,140,1365,132,
%T A109849 5313,120,225,104,189,84,145,60,93,32,33,544,3255,180,5365,1596,2457,
%U A109849 520,9225,840,228459,132,4095,3220,13395,144,833,400,255,364,3445,108,1155
%N A109849 a(1) = 1, a(2) = 2; a(n) = lcm(n, a(n-2)), a(n+1) = lcm((n+1), a(n-3)) and so on until a(2n-1) = lcm(2n-1, a(1)). Then a(2n) = lcm(2n, a(2n-2)) and so on.
%C A109849 Another bootstrap sequence. 12 appears twice.
%C A109849 12 60 65 104 120 132 144 252 255 400 912 1008 1020 1980 2112 2457 4092 4095 ... are the smallest numbers that appear twice, with 4095 being the smallest number that appears three times. - _Joshua Zucker_, May 04 2006
%H A109849 Ivan Neretin, <a href="/A109849/b109849.txt">Table of n, a(n) for n = 1..8193</a>
%F A109849 For n > 2, a(n) = lcm(n, a(A080079(n-2))). - _Ivan Neretin_, Apr 30 2016
%Y A109849 Cf. A109850.
%K A109849 nonn
%O A109849 1,2
%A A109849 _Amarnath Murthy_, Jul 06 2005
%E A109849 More terms from _Joshua Zucker_, May 04 2006