a(n) = A001209(n) + 1.

Terms

a(0) =1a(1) =5a(2) =13a(3) =25a(4) =45a(5) =72a(6) =115a(7) =166a(8) =235a(9) =327a(10) =428a(11) =548a(12) =709a(13) =874a(14) =1095a(15) =1384a(16) =1651a(17) =1936a(18) =2305a(19) =2783a(20) =3325a(21) =3813a(22) =4369a(23) =5131a(24) =5893a(25) =6746a(26) =7881a(27) =8914a(28) =9920a(29) =11082