This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A219878 #6 Jul 23 2025 00:45:27 %S A219878 6,11,47,146,410,1069,2701,6645,15787,36047,79071,166909,339837, %T A219878 668982,1276058,2363344,4258060,7476554,12815234,21476998,35244068, %U A219878 56710659,89591851,139128423,212611297,320053673,475043961,695818283,1006597679 %N A219878 Number of nX3 arrays of the minimum value of corresponding elements and their horizontal, diagonal or antidiagonal neighbors in a random, but sorted with lexicographically nondecreasing rows and nonincreasing columns, 0..2 nX3 array. %C A219878 Column 3 of A219883 %H A219878 R. H. Hardin, <a href="/A219878/b219878.txt">Table of n, a(n) for n = 1..210</a> %F A219878 Empirical: a(n) = (1/19958400)*n^11 + (1/907200)*n^10 - (1/72576)*n^9 + (29/120960)*n^8 + (31/28800)*n^7 - (263/10800)*n^6 + (175169/362880)*n^5 - (1469677/362880)*n^4 + (901433/56700)*n^3 + (759737/50400)*n^2 - (837073/3960)*n + 342 for n>4 %e A219878 Some solutions for n=3 %e A219878 ..1..0..0....2..0..0....0..0..0....1..0..0....2..1..1....1..0..0....1..0..1 %e A219878 ..1..0..1....2..0..1....0..0..0....1..0..1....2..1..1....1..0..1....1..0..0 %e A219878 ..1..2..1....2..1..2....1..0..0....2..1..1....2..1..2....2..2..2....1..0..0 %K A219878 nonn %O A219878 1,1 %A A219878 _R. H. Hardin_ Nov 30 2012