a(1)=1, a(n) = a(n-1) + n^5 if n odd, a(n) = a(n-1) + n^4 if n is even.

Terms

a(0) =1a(1) =17a(2) =260a(3) =516a(4) =3641a(5) =4937a(6) =21744a(7) =25840a(8) =84889a(9) =94889a(10) =255940a(11) =276676a(12) =647969a(13) =686385a(14) =1445760a(15) =1511296a(16) =2931153a(17) =3036129a(18) =5512228a(19) =5672228a(20) =9756329a(21) =9990585a(22) =16426928a(23) =16758704a(24) =26524329a(25) =26981305a(26) =41330212a(27) =41944868a(28) =62456017