Sequence and first differences include all square numbers exactly once.

Terms

a(0) =1a(1) =5a(2) =14a(3) =30a(4) =55a(5) =91a(6) =140a(7) =204a(8) =285a(9) =385a(10) =506a(11) =650a(12) =819a(13) =1015a(14) =1240a(15) =1496a(16) =1785a(17) =2109a(18) =2470a(19) =2870a(20) =3311a(21) =3795a(22) =4324a(23) =4900a(24) =5525a(25) =6201a(26) =6930a(27) =7714a(28) =8555a(29) =9455