OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..1000
EXAMPLE
a(2) = 6: {1,3}, {1,7}, {2,6}, {3,5}, {4,8}, {5,7}.
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Aug 29 2018
STATUS
approved