A219681 Number of nX3 arrays of the minimum value of corresponding elements and their horizontal, vertical or antidiagonal neighbors in a random, but sorted with lexicographically nondecreasing rows and nonincreasing columns, 0..2 nX3 array.
6, 8, 31, 99, 269, 655, 1506, 3356, 7278, 15335, 31362, 62286, 120292, 226281, 415250, 744464, 1305597, 2242405, 3775972, 6240154, 10130551, 16171179, 25404010, 39307716, 59953312, 90205963, 133984022, 196588422, 285117878, 408987989
Offset: 1
Keywords
Examples
Some solutions for n=3 ..0..0..0....2..1..1....0..0..0....1..0..0....1..0..0....1..0..0....0..0..0 ..0..0..0....2..1..1....0..0..0....1..0..0....0..0..0....1..0..0....0..0..0 ..2..1..1....2..1..1....1..1..1....1..1..2....0..0..2....2..0..0....2..0..0
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Formula
Empirical: a(n) = (1/39916800)*n^11 - (1/3628800)*n^10 + (1/362880)*n^9 + (5/24192)*n^8 - (5639/1209600)*n^7 + (11267/172800)*n^6 - (26249/90720)*n^5 - (45251/36288)*n^4 + (5226461/226800)*n^3 - (303403/3150)*n^2 + (229729/1386)*n - 88 for n>4
Comments