a(n) is the index of the first occurrence of n in A331284.

Terms

a(0) =1a(1) =8a(2) =27a(3) =108a(4) =180a(5) =396a(6) =672a(7) =1056a(8) =1372a(9) =1760a(10) =2352a(11) =3087a(12) =3696a(13) =3744a(14) =4896a(15) =5733a(16) =7497a(17) =9724a(18) =11907a(19) =13600a(20) =15200a(21) =18513a(22) =19773a(23) =23940a(24) =24752a(25) =28917a(26) =32319a(27) =33534a(28) =42282a(29) =45472