Number of nX4 0..1 arrays with no element equal to more than two of its horizontal, vertical and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.
A280806
Number of nX4 0..1 arrays with no element equal to more than two of its horizontal, vertical and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.
Terms
- a(0) =0a(1) =18a(2) =332a(3) =2146a(4) =9715a(5) =37644a(6) =133067a(7) =440282a(8) =1387898a(9) =4213683a(10) =12419791a(11) =35750871a(12) =100948088a(13) =280549719a(14) =769389206a(15) =2086323089a(16) =5602827011a(17) =14920267585a(18) =39440232733a(19) =103577644060a(20) =270436207834a(21) =702418367935
External references
- oeis: A280806