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A069306
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
5, 12, 29, 70, 169, 408, 985, 2378, 5741, 13860, 33461, 80782, 195025, 470832, 1136689, 2744210, 6625109, 15994428, 38613965, 93222358, 225058681, 543339720, 1311738121, 3166815962, 7645370045, 18457556052, 44560482149, 107578520350, 259717522849, 627013566048, 1513744654945, 3654502875938
OFFSET
2,1
FORMULA
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
a(n) = 2*a(n-1)+a(n-2). [Philippe Deléham, Nov 20 2008]
MATHEMATICA
LinearRecurrence[{2, 1}, {5, 12}, 50] (* Paolo Xausa, Jul 19 2024 *)
CROSSREFS
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).
Cf. A069294-A069305 (by columns).
Sequence in context: A000465 A283506 A266471 * A277088 A009412 A009428
KEYWORD
nonn,easy
AUTHOR
R. H. Hardin, Mar 14 2002
STATUS
approved