%I #9 Oct 13 2020 03:26:20
%S 1,3,11,42,163,639,2520,9976,39595,157441,626859,2498318,9964308,
%T 39764292,158756360,634044576,2532959099,10121210373,40449588625,
%U 161680869046,646330342699,2584001013295,10331554755044,41311180250504
%N Number of sequences of n integers p(i) i=0..n-1 with 0<=p(i)<=2*i and -2<p(i)-p(i-1)<=2
%C Paths down a n-high staggered-grid minimally right-leaning right triangle with interior neighbor fanout 2*2.
%H R. H. Hardin, <a href="/A180907/b180907.txt">Table of n, a(n) for n=1..100</a>
%H M. Wallner, <a href="http://dmg.tuwien.ac.at/drmota/Thesis_Wallner.pdf">Lattice Path Combinatorics</a>, Diplomarbeit, Institut für Diskrete Mathematik und Geometrie der Technischen Universität Wien, 2013.
%Y Column 2 of A180915.
%K nonn
%O 1,2
%A _R. H. Hardin_ Sep 23 2010