OFFSET
0,2
EXAMPLE
a(1) = 16: 13254, 14253, 14352, 15243, 15342, 23154, 24153, 24351, 25143, 25341, 34152, 34251, 35142, 35241, 45132, 45231.
a(2) = 936: 1213243545, 1213254534, 1214243535, 1214253435, ..., 4545121323, 4545132312, 4545231213, 4545231312.
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Sep 08 2016
STATUS
approved