A227021 Number of n X 2 (0,1,2) arrays of permanents of 2 X 2 subblocks of some (n+1) X 3 binary array with rows and columns of the latter in lexicographically nondecreasing order.

7, 26, 72, 171, 368, 729, 1343, 2325, 3819, 6001, 9082, 13311, 18978, 26417, 36009, 48185, 63429, 82281, 105340, 133267, 166788, 206697, 253859, 309213, 373775, 448641, 534990, 634087, 747286, 876033, 1021869, 1186433, 1371465, 1578809

Offset: 1

Author

R. H. Hardin, Jun 27 2013

Keywords

• nonn

Examples

			Some solutions for n=4:
..0..0....0..0....0..1....1..2....0..1....0..0....0..1....0..0....0..0....1..1
..0..1....0..1....0..0....2..2....0..0....0..0....1..0....0..2....1..1....1..1
..2..1....0..0....0..0....2..2....1..0....1..2....1..0....0..2....0..0....2..1
..2..2....1..1....1..0....2..2....0..0....2..2....2..0....0..2....0..0....2..2
		

Links

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

Crossrefs

Column 2 of A227025.

Formula

Empirical: a(n) = (1/40)*n^5 + (1/3)*n^4 - (1/8)*n^3 + (5/3)*n^2 + (141/10)*n - 15 for n>2.

Conjectures from Colin Barker, Sep 06 2018: (Start)

G.f.: x*(7 - 16*x + 21*x^2 - 11*x^3 + 7*x^4 - 6*x^5 + x^7) / (1 - x)^6.

a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>6.

(End)