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A263587 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 1 or 2, and rows and columns in increasing lexicographic order. 1
1, 6, 12, 31, 89, 230, 536, 1171, 2439, 4882, 9470, 17935, 33331, 60994, 110208, 197059, 349285, 614522, 1074316, 1867855, 3232059, 5569206, 9560842, 16359331, 27909479, 47487870, 80606196, 136522471, 230766449, 389355662, 655827200 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

FORMULA

Empirical: a(n) = 4*a(n-1) - 5*a(n-2) + 2*a(n-3) - 2*a(n-5) + 3*a(n-6) - a(n-8) for n>9.

Empirical g.f.: x*(1 + 2*x - 7*x^2 + 11*x^3 + 13*x^4 + 7*x^5 + 8*x^6 + 5*x^7 + 2*x^8) / ((1 - x)^2*(1 + x^2)*(1 - x - x^2)^2). - Colin Barker, Jan 02 2019

EXAMPLE

Some solutions for n=4:

..1..3..6..8..9....1..5..7..8..9....2..5..6..8..9....1..2..3..8..9

..7..0..5..2..4....6..0..2..3..4....7..0..1..3..4....6..0..5..4..7

CROSSREFS

Row 1 of A263586.

Sequence in context: A152522 A096356 A065992 * A085611 A122608 A268283

Adjacent sequences: A263584 A263585 A263586 * A263588 A263589 A263590

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 22 2015

STATUS

approved

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Last modified November 28 02:51 EST 2022. Contains 358406 sequences. (Running on oeis4.)