%I #9 Jun 07 2017 20:16:29
%S 0,6,108,2598,123750,12994248,3114709914,1730766715308,
%T 2248937669398650,6877862090075063484,49790967547432817528562,
%U 857275977287938332061154856,35233501393224883314185777947590
%N Number of (undirected) paths in the n-triangular grid graph.
%C Paths of length zero are not counted here.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/GraphPath.html">Graph Path</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/TriangularGridGraph.html">Triangular Grid Graph</a>
%e a(1) = 6:
%e : o : o : o : o : o : o
%e : : / : \ : / \ : \ : /
%e : o---o : o o : o o : o o : o---o : o---o .
%Y Cf. A020874, A266513, A112675, A112676.
%K nonn,more
%O 0,2
%A _Eric W. Weisstein_, Jun 05 2017
%E a(7)-a(12) from _Andrew Howroyd_, Jun 07 2017