Number of ways to reciprocally link elements of a 4 X n array either to themselves or to exactly two horizontal and antidiagonal neighbors, without consecutive collinear links.

A220709

Number of ways to reciprocally link elements of a 4 X n array either to themselves or to exactly two horizontal and antidiagonal neighbors, without consecutive collinear links.

Terms

    a(0) =1a(1) =1a(2) =5a(3) =13a(4) =37a(5) =105a(6) =298a(7) =846a(8) =2404a(9) =6826a(10) =19394a(11) =55081a(12) =156473a(13) =444445a(14) =1262497a(15) =3586113a(16) =10186570a(17) =28935186a(18) =82191652a(19) =233468038a(20) =663174914a(21) =1883771569a(22) =5350922525a(23) =15199487245a(24) =43174696525a(25) =122639283705a(26) =348361331050

External references