login
A061703
G.f.: 2*x*(2-2*x-3*x^2+2*x^3)/((1-3*x-x^2+x^3)*(1-x)).
2
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
0,2
REFERENCES
R. P. Stanley, Enumerative Combinatorics I, Example 4.7.17.
CROSSREFS
Row sums of A061702, A000183.
Sequence in context: A361476 A077994 A077843 * A126948 A131593 A340492
KEYWORD
easy,nonn
AUTHOR
Vladeta Jovovic, Jun 18 2001
STATUS
approved