Exponential convolution of central polygonal numbers (A000124) with themselves.

Terms

a(0) =1a(1) =4a(2) =16a(3) =62a(4) =230a(5) =812a(6) =2728a(7) =8752a(8) =26944a(9) =80000a(10) =230144a(11) =644096a(12) =1759744a(13) =4707328a(14) =12359680a(15) =31920128a(16) =81231872a(17) =204013568a(18) =506331136a(19) =1243217920a(20) =3022913536a(21) =7285243904a(22) =17415274496a(23) =41321234432a(24) =97370767360a(25) =227993976832a(26) =530713673728