Second differences of A037260.

Terms

a(0) =4a(1) =11a(2) =19a(3) =29a(4) =41a(5) =54a(6) =68a(7) =83a(8) =99a(9) =117a(10) =137a(11) =158a(12) =180a(13) =203a(14) =227a(15) =252a(16) =279a(17) =307a(18) =337a(19) =368a(20) =400a(21) =433a(22) =467a(23) =502a(24) =539a(25) =577a(26) =616a(27) =656a(28) =698a(29) =741