A221950 - OEIS

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A221950

G.f.: 1/(1 - x - x^2 - 2*x^3 - 3*x^4 - 2*x^5 - x^6).

1, 1, 2, 5, 12, 26, 57, 127, 284, 632, 1405, 3126, 6958, 15485, 34458, 76679, 170638, 379730, 845028, 1880472, 4184690, 9312363, 20723179, 46116124, 102624071, 228373494, 508208766, 1130937495, 2516720889, 5600560664, 12463153900, 27734759853, 61719281504, 137346410422, 305642515549, 680158637002, 1513584491513, 3368240713740, 7495482128252

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OFFSET

0,3

LINKS

Table of n, a(n) for n=0..38.

Michael Dairyko, Lara Pudwell, Samantha Tyner, Casey Wynn, Non-contiguous pattern avoidance in binary trees. Electron. J. Combin. 19 (2012), no. 3, Paper 22, 21 pp. MR2967227.

Index entries for linear recurrences with constant coefficients, signature (1,1,2,3,2,1).

MATHEMATICA

LinearRecurrence[{1, 1, 2, 3, 2, 1}, {1, 1, 2, 5, 12, 26}, 40] (* Harvey P. Dale, Dec 19 2014 *)

CROSSREFS

Sequence in context: A125180 A073778 A033490 * A116716 A128812 A241692

Adjacent sequences: A221947 A221948 A221949 * A221951 A221952 A221953

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Feb 01 2013

STATUS

approved