Odd square pyramidal numbers.

Terms

a(0) =1a(1) =5a(2) =55a(3) =91a(4) =285a(5) =385a(6) =819a(7) =1015a(8) =1785a(9) =2109a(10) =3311a(11) =3795a(12) =5525a(13) =6201a(14) =8555a(15) =9455a(16) =12529a(17) =13685a(18) =17575a(19) =19019a(20) =23821a(21) =25585a(22) =31395a(23) =33511a(24) =40425a(25) =42925a(26) =51039a(27) =53955a(28) =63365a(29) =66729