178990080

Appears in sequences

• Number of self-complementary 3-multigraphs on n nodes.at n=11A052107
• Consider a (hollow) triangle with n cells on each edge, for a total of 3(n-1) cells if n>1, or 1 cell if n=1; a(n) is number of ways of labeling cells with 0's and 1's; triangle may be rotated and turned over.at n=10A061709