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A263603 Number of (1+1) X (n+1) arrays of permutations of 0..n*2+1 filled by rows with each element moved a city block distance of 0 or 2, and rows and columns in increasing lexicographic order. 1
2, 7, 15, 27, 55, 109, 199, 347, 595, 1005, 1671, 2751, 4507, 7357, 11971, 19439, 31531, 51105, 82779, 134031, 216967, 351169, 568315, 919667, 1488175, 2408049, 3896439, 6304707, 10201375, 16506325, 26707951, 43214531, 69922747, 113137557 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = 3*a(n-1) - 3*a(n-2) + 2*a(n-3) - a(n-4) - a(n-5) + a(n-6) for n>8.

Empirical g.f.: x*(2 + x - x^3 + 7*x^4 + 4*x^5 + 3*x^6 + 2*x^7) / ((1 - x)^2*(1 + x^2)*(1 - x - x^2)). - Colin Barker, Jan 02 2019

EXAMPLE

Some solutions for n=4:

..0..3..4..7..8....0..1..2..3..4....0..1..2..3..4....0..1..2..3..4

..1..2..5..6..9....5..6..7..8..9....5..6..9..8..7....7..8..5..6..9

CROSSREFS

Row 1 of A263602.

Sequence in context: A323038 A113422 A061802 * A003452 A000148 A147672

Adjacent sequences:  A263600 A263601 A263602 * A263604 A263605 A263606

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 22 2015

STATUS

approved

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Last modified April 24 19:49 EDT 2019. Contains 322446 sequences. (Running on oeis4.)