First differences give (essentially) A028242.

Terms

a(0) =1a(1) =4a(2) =9a(3) =13a(4) =19a(5) =24a(6) =31a(7) =37a(8) =45a(9) =52a(10) =61a(11) =69a(12) =79a(13) =88a(14) =99a(15) =109a(16) =121a(17) =132a(18) =145a(19) =157a(20) =171a(21) =184a(22) =199a(23) =213a(24) =229a(25) =244a(26) =261a(27) =277a(28) =295a(29) =312