First differences of A037260.

Terms

a(0) =2a(1) =6a(2) =17a(3) =36a(4) =65a(5) =106a(6) =160a(7) =228a(8) =311a(9) =410a(10) =527a(11) =664a(12) =822a(13) =1002a(14) =1205a(15) =1432a(16) =1684a(17) =1963a(18) =2270a(19) =2607a(20) =2975a(21) =3375a(22) =3808a(23) =4275a(24) =4777a(25) =5316a(26) =5893a(27) =6509a(28) =7165a(29) =7863