a(n) is the number of chiral pairs of color patterns (set partitions) in a row of length n using exactly 3 colors (subsets).
A320526
a(n) is the number of chiral pairs of color patterns (set partitions) in a row of length n using exactly 3 colors (subsets).
Terms
- a(0) =0a(1) =0a(2) =0a(3) =2a(4) =10a(5) =40a(6) =141a(7) =464a(8) =1480a(9) =4600a(10) =14145a(11) =43052a(12) =130480a(13) =393820a(14) =1186521a(15) =3568784a(16) =10725760a(17) =32213200a(18) =96714465a(19) =290284052a(20) =871142800a(21) =2613981700a(22) =7843080201a(23) =23531425304a(24) =70598731840a(25) =211804847800a(26) =635432109585
External references
- oeis: A320526