Sum of the next n positive integers repeated (A008619).

Terms

a(0) =1a(1) =3a(2) =8a(3) =18a(4) =34a(5) =57a(6) =89a(7) =132a(8) =187a(9) =255a(10) =338a(11) =438a(12) =556a(13) =693a(14) =851a(15) =1032a(16) =1237a(17) =1467a(18) =1724a(19) =2010a(20) =2326a(21) =2673a(22) =3053a(23) =3468a(24) =3919a(25) =4407a(26) =4934a(27) =5502a(28) =6112a(29) =6765