%I #18 May 08 2021 11:30:41
%S 1,4,28,264,2860,33592,416024,5348880,70715340,955277400,13128240840,
%T 182965127280,2579808294648,36734706144304,527495903500720,
%U 7629973004184608,111068129754096396,1625888084299461528,23919596771720906984,353467725574013402800
%N Certain directed lattice paths.
%C See Dziemianczuk (2014) for precise definition.
%H Lars Blomberg, <a href="/A260775/b260775.txt">Table of n, a(n) for n = 0..100</a>
%H M. Dziemianczuk, <a href="http://arxiv.org/abs/1410.5747">On Directed Lattice Paths With Additional Vertical Steps</a>, arXiv preprint arXiv:1410.5747 [math.CO], 2014.
%H Maciej DziemiaĆczuk, <a href="https://doi.org/10.1016/j.disc.2015.11.001">On directed lattice paths with vertical steps</a>, Discrete Math., 339 (2016), 1116-1139.
%H Alex Hall, <a href="https://alexmojaki.github.io/oeis-explorer/">OEIS explorer</a>
%F See Dziemianczuk (2014) Equation (36b) with N=2.
%F a(n) = 2 * A000108(2*n) for n > 0. [Agrees with the reference, found using OEIS explorer.] - _Andrey Zabolotskiy_, May 08 2021
%Y Cf. A000108, A260769, A260770, A260771, A260772, A260773, A260774, A260776.
%K nonn,easy
%O 0,2
%A _N. J. A. Sloane_, Jul 30 2015
%E More terms from _Lars Blomberg_, Aug 01 2015