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Number of 2 X n binary arrays with a path of adjacent 1's from upper left corner to anywhere in right hand column.
31

%I #32 Jul 19 2024 19:06:15

%S 5,12,29,70,169,408,985,2378,5741,13860,33461,80782,195025,470832,

%T 1136689,2744210,6625109,15994428,38613965,93222358,225058681,

%U 543339720,1311738121,3166815962,7645370045,18457556052,44560482149,107578520350,259717522849,627013566048,1513744654945,3654502875938

%N Number of 2 X n binary arrays with a path of adjacent 1's from upper left corner to anywhere in right hand column.

%H Indranil Ghosh, <a href="/A069306/b069306.txt">Table of n, a(n) for n = 2..2607</a>

%H Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a>

%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,1).

%F G.f.: x^2(2x+5)/(1-2x-x^2). a(n) = A000129(n+1), as proved by Tomislav Doslic. - _Ralf Stephan_, Nov 16 2004

%F a(n) = 2*a(n-1)+a(n-2). [_Philippe Deléham_, Nov 20 2008]

%t LinearRecurrence[{2, 1}, {5, 12}, 50] (* _Paolo Xausa_, Jul 19 2024 *)

%Y Cf. A069307 (3 X n), A069308 (4 X n), A069309 (5 X n), A069310 (6 X n), A069311 (7 X n), A069312 (8 X n), A069313 (9 X n), A069314 (10 X n), A069315 (11 X n), A069316 (12 X n), A069317 (13 X n), A069318 (14 X n), A069319 (15 X n), A069320 (16 X n).

%Y Cf. A069294-A069305 (by columns).

%Y Cf. A000129, A048624, A077985.

%K nonn,easy

%O 2,1

%A _R. H. Hardin_, Mar 14 2002