Partial sums of n 3-spaced triangular numbers beginning with t(3), e.g., a(2) = t(3)+t(6) = 6+21 = 27.

A085788

Partial sums of n 3-spaced triangular numbers beginning with t(3), e.g., a(2) = t(3)+t(6) = 6+21 = 27.

Terms

    a(0) =6a(1) =27a(2) =72a(3) =150a(4) =270a(5) =441a(6) =672a(7) =972a(8) =1350a(9) =1815a(10) =2376a(11) =3042a(12) =3822a(13) =4725a(14) =5760a(15) =6936a(16) =8262a(17) =9747a(18) =11400a(19) =13230a(20) =15246a(21) =17457a(22) =19872a(23) =22500a(24) =25350a(25) =28431a(26) =31752a(27) =35322a(28) =39150a(29) =43245

External references