a(n) = floor((n + 1/2)^6).

Terms

a(0) =0a(1) =11a(2) =244a(3) =1838a(4) =8303a(5) =27680a(6) =75418a(7) =177978a(8) =377149a(9) =735091a(10) =1340095a(11) =2313060a(12) =3814697a(13) =6053445a(14) =9294114a(15) =13867245a(16) =20179187a(17) =28722900a(18) =40089475a(19) =54980371a(20) =74220378a(21) =98771297a(22) =129746337a(23) =168425239a(24) =216270112a(25) =274941996