Principal diagonal of the convolution array A213548.

Terms

a(0) =1a(1) =12a(2) =53a(3) =155a(4) =360a(5) =721a(6) =1302a(7) =2178a(8) =3435a(9) =5170a(10) =7491a(11) =10517a(12) =14378a(13) =19215a(14) =25180a(15) =32436a(16) =41157a(17) =51528a(18) =63745a(19) =78015a(20) =94556a(21) =113597a(22) =135378a(23) =160150a(24) =188175a(25) =219726a(26) =255087a(27) =294553a(28) =338430a(29) =387035