A240461 - OEIS

A240461

Number of 2 X n 0..3 arrays with no element equal to one plus the sum of elements to its left or three plus the sum of the elements above it or one plus the sum of the elements diagonally to its northwest, modulo 4.

5, 21, 89, 375, 1583, 6685, 28241, 119319, 504151, 2130189, 9000729, 38030999, 160693343, 678981661, 2868918401, 12122113399, 51219871687, 216420616013, 914447487881, 3863838035639, 16325972308111, 68982542575773

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OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = 6*a(n-1) - 7*a(n-2) - 4*a(n-3) + 8*a(n-4).

Empirical g.f.: x*(5 - 9*x - 2*x^2 + 8*x^3) / (1 - 6*x + 7*x^2 + 4*x^3 - 8*x^4). - Colin Barker, Oct 29 2018

EXAMPLE

Some solutions for n=4:

..2..2..2..0....0..2..0..2....0..2..0..2....2..2..2..0....0..0..0..0

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

CROSSREFS

Row 2 of A240460.

Sequence in context: A267268 A355117 A273643 * A273860 A099843 A015448

Adjacent sequences: A240458 A240459 A240460 * A240462 A240463 A240464

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 05 2014

STATUS

approved