OFFSET
0,3
COMMENTS
a(n)=trace(A^n)/6 where A is the adjacency matrix of the graph obtained by constructing external triangles on the sides of a triangle (or equivalently, taking a triangle and its midpoint triangle). A Lucas Jacobsthal product. Compare with A093042.
LINKS
Index entries for linear recurrences with constant coefficients, signature (1,7,2,-4).
FORMULA
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, May 16 2004
STATUS
approved