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

1,1

Links

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

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)

Example

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

Crossrefs

Column 2 of A227025.

Sequence in context: A269700 A006325 A053346 * A180669 A027964 A183957

Adjacent sequences: A227018 A227019 A227020 * A227022 A227023 A227024

Keyword

nonn

Author

R. H. Hardin, Jun 27 2013

Status

approved