login
A219774
Number of 3 X n arrays of the minimum value of corresponding elements and their horizontal or antidiagonal neighbors in a random, but sorted with lexicographically nondecreasing rows and columns, 0..1 3 X n array.
1
4, 6, 14, 33, 65, 114, 189, 298, 450, 655, 924, 1269, 1703, 2240, 2895, 3684, 4624, 5733, 7030, 8535, 10269, 12254, 14513, 17070, 19950, 23179, 26784, 30793, 35235, 40140, 45539, 51464, 57948, 65025, 72730, 81099, 90169, 99978, 110565, 121970, 134234
OFFSET
1,1
COMMENTS
Row 3 of A219773.
LINKS
FORMULA
Empirical: a(n) = (1/24)*n^4 + (1/4)*n^3 - (13/24)*n^2 + (17/4)*n for n>4.
Conjectures from Colin Barker, Jul 27 2018: (Start)
G.f.: x*(4 - 14*x + 24*x^2 - 17*x^3 + 5*x^5 + 3*x^6 - 6*x^7 + 2*x^8) / (1 - x)^5.
a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>9.
(End)
EXAMPLE
Some solutions for n=3:
..0..0..0....0..0..0....0..0..1....0..0..1....0..0..0....0..0..0....0..0..0
..0..0..0....0..0..0....0..0..0....0..0..1....0..1..1....0..0..0....0..0..1
..1..0..1....0..1..1....0..0..0....1..1..1....1..1..1....1..0..0....1..1..1
CROSSREFS
Cf. A219773.
Sequence in context: A319766 A373567 A108516 * A274208 A077068 A277059
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 27 2012
STATUS
approved