Sum of tetrahedral numbers A000292(k), with k in the reduced residue system modulo n.

Terms

a(0) =0a(1) =1a(2) =5a(3) =11a(4) =35a(5) =36a(6) =126a(7) =130a(8) =264a(9) =260a(10) =715a(11) =406a(12) =1365a(13) =952a(14) =1530a(15) =1716a(16) =3876a(17) =1830a(18) =5985a(19) =3300a(20) =5796a(21) =5500a(22) =12650a(23) =5460a(24) =15075a(25) =10556a(26) =16965a(27) =12810a(28) =31465a(29) =9920