OFFSET
0,3
LINKS
Rémy Sigrist, C program
EXAMPLE
{{{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.
PROG
(C) See Links section.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Jonas Wallgren, Mar 17 2005
EXTENSIONS
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
STATUS
approved