Partial sums of the odd triangular numbers (A014493).

Terms

a(0) =1a(1) =4a(2) =19a(3) =40a(4) =85a(5) =140a(6) =231a(7) =336a(8) =489a(9) =660a(10) =891a(11) =1144a(12) =1469a(13) =1820a(14) =2255a(15) =2720a(16) =3281a(17) =3876a(18) =4579a(19) =5320a(20) =6181a(21) =7084a(22) =8119a(23) =9200a(24) =10425a(25) =11700a(26) =13131a(27) =14616a(28) =16269a(29) =17980