A061703 G.f.: 2*x*(2-2*x-3*x^2+2*x^3)/((1-3*x-x^2+x^3)*(1-x)).

0, 4, 12, 34, 108, 344, 1104, 3546, 11396, 36628, 117732, 378426, 1216380, 3909832, 12567448, 40395794, 129844996, 417363332, 1341539196, 4312135922, 13860583628, 44552347608, 143205490528, 460308235562, 1479577849604

Offset: 0

Author

Vladeta Jovovic, Jun 18 2001

Keywords

• easy
• nonn

References

• R. P. Stanley, Enumerative Combinatorics I, Example 4.7.17.

Links

• Index entries for linear recurrences with constant coefficients, signature (4,-2,-2,1)

Crossrefs

Row sums of A061702, A000183.