Principal diagonal of the convolution array A213762.

Terms

a(0) =1a(1) =11a(2) =43a(3) =127a(4) =331a(5) =807a(6) =1891a(7) =4319a(8) =9691a(9) =21463a(10) =47059a(11) =102351a(12) =221131a(13) =475079a(14) =1015747a(15) =2162623a(16) =4587451a(17) =9699255a(18) =20447155a(19) =42991535a(20) =90177451a(21) =188743591a(22) =394264483a(23) =822083487a(24) =1711275931a(25) =3556769687a(26) =7381974931