Number of nX1 0..3 arrays with values 0..3 introduced in row major order, the number of instances of each value within one of each other, and every element equal to two or fewer horizontal or vertical neighbors.
A199516
Number of nX1 0..3 arrays with values 0..3 introduced in row major order, the number of instances of each value within one of each other, and every element equal to two or fewer horizontal or vertical neighbors.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =10a(5) =45a(6) =105a(7) =105a(8) =1260a(9) =6300a(10) =15400a(11) =15400a(12) =200200a(13) =1051050a(14) =2627625a(15) =2627625a(16) =35735700a(17) =192972780a(18) =488864376a(19) =488864376a(20) =6844101264a(21) =37642556952a(22) =96197645544a(23) =96197645544
External references
- oeis: A199516