OFFSET
1,4
COMMENTS
Alternatively a(n) is the number of distinct five-triplet sets produced by A(n)-D(n); that is, a(n) = |A(n)-D(n)|, where the sequences of sets A(n), B(n) and C(n) are introduced in A384479 and D(n) = B(n) U C(n).
LINKS
Janaka Rodrigo, Sets of A(n)-D(n) in Triplets Form
EXAMPLE
A(3) = {{(1,1,2), (1,1,3), (1,2,2), (1,2,3), (2,2,3)}, {(1,1,1), (1,1,2), (1,1,3), (1,3,3), (2,2,3)}}.
B(3) = {{(1,1,2), (1,1,3), (1,2,2), (1,2,3), (2,2,3)}}.
C(3) = {}.
D(3) = B(3) U C(3) = {{(1,1,2), (1,1,3), (1,2,2), (1,2,3), (2,2,3)}}.
A(3)-D(3) = {{(1,1,1), (1,1,2), (1,1,3), (1,3,3), (2,2,3)}}.
Therefore, a(3) = 1.
CROSSREFS
KEYWORD
nonn
AUTHOR
Janaka Rodrigo, Jun 08 2025
EXTENSIONS
a(11)-a(37) from Jinyuan Wang, Aug 04 2025
STATUS
approved
