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A264535 Number of (2+1) X (n+1) arrays of permutations of 0..n*3+2 with each element having directed index change -2,-2 -1,0 0,1 or 1,0. 1
0, 4, 2, 1, 16, 16, 16, 68, 97, 128, 328, 548, 838, 1729, 3056, 5056, 9536, 17096, 29441, 53584, 96144, 168804, 303114, 542785, 961504, 1718224, 3071248, 5461836, 9744865, 17398576, 30992536, 55270596, 98619022, 175791233, 313466656, 559141632 (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-3) + 2*a(n-4) + 2*a(n-5) - 2*a(n-9) - a(n-10).

Empirical g.f.: x^2*(4 + 2*x + x^2 - 2*x^6 - x^7) / ((1 + x + x^2 - x^3 - x^4)*(1 - x - 2*x^3 - x^5 - x^6)). - Colin Barker, Jan 08 2019

EXAMPLE

All solutions for n=4:

.12.13.14..2..3

..0..1..6..7..4

..5.10.11..8..9

CROSSREFS

Row 2 of A264534.

Sequence in context: A143777 A236830 A269736 * A256039 A152391 A144088

Adjacent sequences:  A264532 A264533 A264534 * A264536 A264537 A264538

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 17 2015

STATUS

approved

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Last modified April 20 17:54 EDT 2019. Contains 322310 sequences. (Running on oeis4.)