OFFSET
1,2
LINKS
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. - From N. J. A. Sloane, Feb 01 2013
Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.
Index entries for linear recurrences with constant coefficients, signature (3,-1,-2).
FORMULA
G.f.: A(x) = (x^3-x+1)*x/((2*x-1)*(x^2+x-1)).
MATHEMATICA
CoefficientList[Series[(x^3-x+1)/((2*x-1)*(x^2+x-1)), {x, 0, 50}], x] (* Stefano Spezia, Nov 29 2018 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Lara Pudwell, Feb 26 2006
STATUS
approved