a(n) = (n+1)^5 - n^5.

Terms

a(0) =1a(1) =31a(2) =211a(3) =781a(4) =2101a(5) =4651a(6) =9031a(7) =15961a(8) =26281a(9) =40951a(10) =61051a(11) =87781a(12) =122461a(13) =166531a(14) =221551a(15) =289201a(16) =371281a(17) =469711a(18) =586531a(19) =723901a(20) =884101a(21) =1069531a(22) =1282711a(23) =1526281a(24) =1803001a(25) =2115751a(26) =2467531a(27) =2861461a(28) =3300781a(29) =3788851