Number of nX2 0..3 arrays with rows and columns lexicographically nondecreasing and every element equal to at least one horizontal or vertical neighbor.
A201619
Number of nX2 0..3 arrays with rows and columns lexicographically nondecreasing and every element equal to at least one horizontal or vertical neighbor.
Terms
- a(0) =4a(1) =16a(2) =56a(3) =211a(4) =718a(5) =2271a(6) =6654a(7) =18191a(8) =46767a(9) =113873a(10) =264247a(11) =587571a(12) =1257743a(13) =2602113a(14) =5220668a(15) =10186777a(16) =19378603a(17) =36016206a(18) =65517188a(19) =116838180a(20) =204546828a(21) =351977489a(22) =595974410a(23) =993932688a(24) =1634127635a(25) =2650699891a(26) =4245165105
External references
- oeis: A201619