a(n) = number of segments (edges) in the configuration A290447(n).

Terms

a(0) =0a(1) =1a(2) =3a(3) =8a(4) =20a(5) =45a(6) =91a(7) =168a(8) =285a(9) =450a(10) =670a(11) =981a(12) =1375a(13) =1902a(14) =2568a(15) =3371a(16) =4326a(17) =5522a(18) =6927a(19) =8639a(20) =10624a(21) =12882a(22) =15489a(23) =18559a(24) =22006a(25) =25904a(26) =30321a(27) =35254a(28) =40728a(29) =46959