0,3

Table of n, a(n) for n=0..19.

Rémy Sigrist, C program

{{{1,2,3,4},{5,6,7,8},{9,10,11,12}}, {{1,2,3,4},{5,7,9,11},{6,8,10,12}}, {{1,3,5,7},{2,4,6,8},{9,10,11,12}}, {{1,4,7,10},{2,5,8,11},{3,6,9,12}}} are the 4 ways to split 1, 2, 3, ..., 12 into 3 arithmetic progressions each with 4 terms. Thus a(3)=4.

(C) See Links section.

Cf. A104429, A104431-A104443, A337520.

Sequence in context: A061152 A307881 A006452 * A298255 A298926 A292157

Adjacent sequences: A104427 A104428 A104429 * A104431 A104432 A104433

nonn,more

Jonas Wallgren, Mar 17 2005

a(11)-a(17) from Alois P. Heinz, Dec 28 2011

a(0)=1 prepended by Alois P. Heinz, Nov 18 2020

a(18)-a(19) from Rémy Sigrist, Feb 07 2022

approved