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A222867 Number of n X 1 0..5 arrays with no element equal to another at a city block distance of exactly two, and new values 0..5 introduced in row major order. 1
1, 2, 3, 7, 20, 67, 254, 1057, 4700, 21847, 104474, 508477, 2501480, 12386227, 61570694, 306778297, 1530678260, 7643776207, 38190084914, 190864134517, 954061999040, 4769534367787, 23845345743134, 119219752001137 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 1 of A222871.

LINKS

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

FORMULA

Empirical: a(n) = 11*a(n-1) - 41*a(n-2) + 61*a(n-3) - 30*a(n-4) for n>6.

Empirical g.f.: x*(1 + x)*(1 - 10*x + 32*x^2 - 37*x^3 + 11*x^4) / ((1 - x)*(1 - 2*x)*(1 - 3*x)*(1 - 5*x)). - Colin Barker, Aug 16 2018

EXAMPLE

All solutions for n=3:

..0....0....0

..1....1....0

..2....1....1

CROSSREFS

Cf. A222871.

Sequence in context: A052402 A300041 A222939 * A222776 A222890 A011968

Adjacent sequences:  A222864 A222865 A222866 * A222868 A222869 A222870

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 07 2013

STATUS

approved

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Last modified March 19 17:21 EDT 2019. Contains 321330 sequences. (Running on oeis4.)