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
Keywords
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)