Number triangle, equal to half of Delannoy square array A008288.

Terms

a(0) =1a(1) =3a(2) =1a(3) =13a(4) =5a(5) =1a(6) =63a(7) =25a(8) =7a(9) =1a(10) =321a(11) =129a(12) =41a(13) =9a(14) =1a(15) =1683a(16) =681a(17) =231a(18) =61a(19) =11a(20) =1a(21) =8989a(22) =3653a(23) =1289a(24) =377a(25) =85a(26) =13a(27) =1a(28) =48639a(29) =19825