Partial sums of n 3-spaced triangular numbers beginning with t(2), e.g., a(2) = t(2) + t(5) = 3 + 15 = 18.

A085789

Partial sums of n 3-spaced triangular numbers beginning with t(2), e.g., a(2) = t(2) + t(5) = 3 + 15 = 18.

Terms

    a(0) =3a(1) =18a(2) =54a(3) =120a(4) =225a(5) =378a(6) =588a(7) =864a(8) =1215a(9) =1650a(10) =2178a(11) =2808a(12) =3549a(13) =4410a(14) =5400a(15) =6528a(16) =7803a(17) =9234a(18) =10830a(19) =12600a(20) =14553a(21) =16698a(22) =19044a(23) =21600a(24) =24375a(25) =27378a(26) =30618a(27) =34104a(28) =37845a(29) =41850

External references