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.

1, 2, 3, 4, 5, 12, 21, 8, 9, 40, 231, 12, 65, 28, 15, 16, 17, 144, 285, 140, 1365, 132, 5313, 120, 225, 104, 189, 84, 145, 60, 93, 32, 33, 544, 3255, 180, 5365, 1596, 2457, 520, 9225, 840, 228459, 132, 4095, 3220, 13395, 144, 833, 400, 255, 364, 3445, 108, 1155

Offset

1,2

Comments

Another bootstrap sequence. 12 appears twice.

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

Links

Ivan Neretin, Table of n, a(n) for n = 1..8193

Formula

For n > 2, a(n) = lcm(n, a(A080079(n-2))). - Ivan Neretin, Apr 30 2016

Crossrefs

Cf. A109850.

Sequence in context: A333390 A367408 A117577 * A007662 A348370 A069469

Adjacent sequences: A109846 A109847 A109848 * A109850 A109851 A109852

Keyword

nonn

Author

Amarnath Murthy, Jul 06 2005

Extensions

More terms from Joshua Zucker, May 04 2006

Status

approved