a(n) = n^6 - 63*n + 63, with n*a(n) + n*(n-1)*63 = n^7.

Terms

a(0) =1a(1) =1a(2) =603a(3) =3907a(4) =15373a(5) =46341a(6) =117271a(7) =261703a(8) =530937a(9) =999433a(10) =1770931a(11) =2985291a(12) =4826053a(13) =7528717a(14) =11389743a(15) =16776271a(16) =24136561a(17) =34011153a(18) =47044747a(19) =63998803a(20) =85764861a(21) =113378581a(22) =148034503a(23) =191101527a(24) =244139113a(25) =308914201a(26) =387418851