41 times triangular numbers.

Terms

a(0) =0a(1) =41a(2) =123a(3) =246a(4) =410a(5) =615a(6) =861a(7) =1148a(8) =1476a(9) =1845a(10) =2255a(11) =2706a(12) =3198a(13) =3731a(14) =4305a(15) =4920a(16) =5576a(17) =6273a(18) =7011a(19) =7790a(20) =8610a(21) =9471a(22) =10373a(23) =11316a(24) =12300a(25) =13325a(26) =14391a(27) =15498a(28) =16646a(29) =17835