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A278621 Number of nX2 0..2 arrays with rows in nondecreasing lexicographic order and columns in nonincreasing lexicographic order, but with exactly one mistake. 1

%I

%S 3,46,357,1952,8518,31605,103546,307087,838936,2138608,5137407,

%T 11719956,25549096,53493458,108027996,211167710,400765157,740380790,

%U 1334456849,2351234708,4056807390,6864961455,11409118950,18644841765,29994129570

%N Number of nX2 0..2 arrays with rows in nondecreasing lexicographic order and columns in nonincreasing lexicographic order, but with exactly one mistake.

%C Column 2 of A278627.

%H R. H. Hardin, <a href="/A278621/b278621.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = (1/1307674368000)*n^15 + (1/12454041600)*n^14 + (149/37362124800)*n^13 + (17/136857600)*n^12 + (3497/1306368000)*n^11 + (241/5806080)*n^10 + (865163/1828915200)*n^9 + (351247/87091200)*n^8 + (2328827/93312000)*n^7 + (698341/6220800)*n^6 + (259070737/718502400)*n^5 + (30620411/39916800)*n^4 + (8765485871/9081072000)*n^3 + (2221837/3603600)*n^2 + (4873/32760)*n

%e Some solutions for n=4

%e ..2..0. .0..0. .1..0. .0..1. .2..0. .0..0. .1..0. .2..2. .2..2. .0..0

%e ..0..0. .2..2. .1..2. .1..2. .2..0. .1..0. .1..2. .1..1. .2..2. .2..1

%e ..2..1. .1..1. .2..2. .2..0. .2..1. .2..2. .2..1. .2..1. .2..2. .0..2

%e ..2..1. .2..0. .0..0. .2..0. .1..2. .0..0. .0..1. .2..2. .0..0. .1..0

%Y Cf. A278627.

%K nonn

%O 1,1

%A _R. H. Hardin_, Nov 24 2016

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Last modified October 18 12:19 EDT 2021. Contains 348067 sequences. (Running on oeis4.)