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A222835 Number of n X 5 0..3 arrays with no element equal to another at a city block distance of exactly two, and new values 0..3 introduced in row major order. 1
19, 384, 648, 1536, 4032, 9600, 22848, 55296, 133824, 322944, 779328, 1881600, 4542912, 10967424, 26477376, 63922176, 154322112, 372566400, 899454528, 2171475456, 5242405824, 12656287104, 30554979648, 73766246400, 178087472832 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 5 of A222838.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 2*a(n-1) + 2*a(n-3) + a(n-4) for n>7.

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

G.f.: x*(19 + 346*x - 120*x^2 + 202*x^3 + 173*x^4 - 144*x^5 - 72*x^6) / ((1 + x^2)*(1 - 2*x - x^2)).

a(n) = 48*((-1+i)*((-i)^n+i^(1+n)) + (1-sqrt(2))^n + (1+sqrt(2))^n) for n>3, where i=sqrt(-1).

(End)

EXAMPLE

Some solutions for n=4:

..0..1..2..0..1....0..0..1..2..2....0..1..2..3..3....0..0..1..2..0

..2..1..3..3..1....3..2..1..3..3....0..1..2..0..1....1..2..3..3..0

..2..0..0..2..2....3..2..0..0..1....2..3..3..0..2....3..2..0..1..1

..3..3..1..1..0....0..1..3..2..1....2..0..1..1..2....3..1..0..2..2

CROSSREFS

Cf. A222838.

Sequence in context: A075839 A158592 A072359 * A094737 A009075 A221584

Adjacent sequences:  A222832 A222833 A222834 * A222836 A222837 A222838

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 06 2013

STATUS

approved

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Last modified October 20 08:20 EDT 2020. Contains 337900 sequences. (Running on oeis4.)