Row sums of triangle A134285, called s2(3)'.

Terms

a(0) =1a(1) =4a(2) =14a(3) =58a(4) =214a(5) =908a(6) =3442a(7) =14444a(8) =56386a(9) =234476a(10) =920490a(11) =3847998a(12) =15165982a(13) =62944212a(14) =250787568a(15) =1036586952a(16) =4132605038a(17) =17106500792a(18) =68303652958a(19) =281749732730