Number of ways to reciprocally link elements of an n X 2 array either to themselves or to exactly one horizontal, vertical or antidiagonal neighbor.
A220547
Number of ways to reciprocally link elements of an n X 2 array either to themselves or to exactly one horizontal, vertical or antidiagonal neighbor.
Terms
- a(0) =2a(1) =8a(2) =29a(3) =108a(4) =401a(5) =1490a(6) =5536a(7) =20569a(8) =76424a(9) =283953a(10) =1055026a(11) =3919944a(12) =14564533a(13) =54114452a(14) =201061985a(15) =747044834a(16) =2775641472a(17) =10312882481a(18) =38317465040a(19) =142368356257a(20) =528968939938
External references
- oeis: A220547