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

Terms

a(0) =1a(1) =2a(2) =8a(3) =18a(4) =78a(5) =206a(6) =872a(7) =2226a(8) =10820a(9) =26558a(10) =129248a(11) =335886a(12) =1630174a(13) =3990978a(14) =21778450a(15) =48749804a(16) =274937594a(17) =650637382a(18) =3598954596a(19) =7610277626a(20) =49741540498a(21) =93757794966a(22) =639655810986