A140961 Number of 3 X n {0,1}-matrices such that: (a) first and second row have a common 1, (b) second and third row have a common 1.

1, 17, 205, 2129, 20341, 184457, 1615405, 13808609, 116015461, 962575097, 7913168605, 64610052689, 524855128981, 4247421698537, 34274519697805, 275985344786369, 2218709434248901, 17815093293410777, 142915542082163005, 1145704555158361649, 9179974972732223221

Offset

1,2

Links

Table of n, a(n) for n=1..21.

Andi Fugard, Counting first-order models (with n individuals) of syllogisms.

Index entries for linear recurrences with constant coefficients, signature (19,-118,240).

Formula

a(n) = 8^n-2*6^n+5^n.

G.f.: x*(2*x-1)/((5*x-1)*(6*x-1)*(8*x-1)). [Colin Barker, Nov 05 2012]

Crossrefs

Cf. A051588.

Sequence in context: A279448 A017897 A016311 * A016306 A021092 A219124

Adjacent sequences: A140958 A140959 A140960 * A140962 A140963 A140964

Keyword

easy,nonn

Author

Andi Fugard, Vladeta Jovovic, Jul 26 2008

Status

approved