A222892 Number of n X 3 0..7 arrays with no element equal to another at a city block distance of exactly two, and new values 0..7 introduced in row major order.

3, 34, 991, 84521, 11047723, 1639681049, 251412693667, 38863548783281, 6019757701002763, 932903107051648169, 144593771181391763827, 22411792379084676340961, 3473818375479216866296603

Offset

1,1

Comments

Column 3 of A222894.

Links

R. H. Hardin, Table of n, a(n) for n = 1..108

Formula

Empirical: a(n) = 211*a(n-1) - 9385*a(n-2) + 110913*a(n-3) - 253890*a(n-4) for n>6.

Conjectures from Colin Barker, Aug 16 2018: (Start)

G.f.: x*(3 - 599*x + 21972*x^2 - 138229*x^3 - 495045*x^4 + 558558*x^5) / ((1 - 3*x)*(1 - 14*x)*(1 - 39*x)*(1 - 155*x)).

a(n) = 3^n + 5*2^(n-1)*7^(n-2) + 14*5^(n-3)*31^(n-2) + 10*39^(n-2) for n>2.

(End)

Example

Some solutions for n=3:
..0..1..2....0..1..1....0..1..2....0..1..2....0..1..2....0..1..2....0..1..2
..3..4..5....0..2..2....3..4..5....3..4..2....2..1..0....3..1..2....3..4..5
..2..0..5....3..3..0....1..6..7....2..0..3....3..4..4....2..0..4....1..4..5

Crossrefs

Cf. A222894.

Sequence in context: A101633 A250093 A054783 * A324234 A366137 A337069

Adjacent sequences: A222889 A222890 A222891 * A222893 A222894 A222895

Keyword

nonn

Author

R. H. Hardin, Mar 08 2013

Status

approved