A206353 - OEIS

A206353

Number of n X 2 0..4 arrays with no element equal to another within two positions in the same row or column, and new values 0..4 introduced in row major order.

1, 4, 17, 120, 884, 6558, 48680, 361422, 2683328, 19922214, 147910952, 1098154590, 8153170064, 60532632918, 449420225720, 3336688521102, 24773006668448, 183925426722054, 1365541253642312, 10138363949208510, 75271562311604144

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OFFSET

1,2

COMMENTS

Column 2 of A206359.

LINKS

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

FORMULA

Empirical: a(n) = 6*a(n-1) + 13*a(n-2) - 18*a(n-3) for n>5.

Empirical g.f.: x*(1 - 2*x - 20*x^2 - 16*x^3 + 15*x^4) / ((1 - x)*(1 - 5*x - 18*x^2)). - Colin Barker, Jun 15 2018

EXAMPLE

Some solutions for n=4: