Convolution of Catalan numbers and powers of 2.

Terms

a(0) =1a(1) =3a(2) =8a(3) =21a(4) =56a(5) =154a(6) =440a(7) =1309a(8) =4048a(9) =12958a(10) =42712a(11) =144210a(12) =496432a(13) =1735764a(14) =6145968a(15) =21986781a(16) =79331232a(17) =288307254a(18) =1054253208a(19) =3875769606a(20) =14315659632a(21) =53097586284a(22) =197677736208a(23) =738415086066