A162024 Number of n X n binary arrays with rows and columns, considered as binary numbers, in nondecreasing order, and all but the outermost row or column zero.

7, 20, 40, 68, 104, 148, 200, 260, 328, 404, 488, 580, 680, 788, 904, 1028, 1160, 1300, 1448, 1604, 1768, 1940, 2120, 2308, 2504, 2708, 2920, 3140, 3368, 3604, 3848, 4100, 4360, 4628, 4904, 5188, 5480, 5780, 6088, 6404, 6728, 7060, 7400, 7748, 8104, 8468

Offset

2,1

Links

R. H. Hardin, Table of n, a(n) for n = 2..100

Formula

Empirical: a(n)= 3*a(n-1) - 3*a(n-2) + a(n-3), n>5. a(n)= A128445(n+1), n>2. - R. J. Mathar, Aug 11 2009

Conjectures from Colin Barker, Mar 24 2018: (Start)

G.f.: x^2*(7 - x + x^2 + x^3) / (1 - x)^3.

a(n) = 4*(2 - 2*n + n^2) for n>2.

(End)

Crossrefs

Sequence in context: A038349 A360226 A100752 * A143058 A298488 A175428

Adjacent sequences: A162021 A162022 A162023 * A162025 A162026 A162027

Keyword

nonn

Author

R. H. Hardin, Jun 25 2009

Status

approved