Number of perfect matchings on a triangular lattice of width 4 and length n.

A309117

Number of perfect matchings on a triangular lattice of width 4 and length n.

Terms

    a(0) =1a(1) =1a(2) =5a(3) =15a(4) =56a(5) =203a(6) =749a(7) =2777a(8) =10293a(9) =38240a(10) =141997a(11) =527593a(12) =1960029a(13) =7282483a(14) =27057400a(15) =100531559a(16) =373522965a(17) =1387822193a(18) =5156442953a(19) =19158736256a(20) =71184183353a(21) =264484479633a(22) =982690786037

External references