a(n) = T(n,n-4), array T as in A055818.

Terms

a(0) =1a(1) =23a(2) =60a(3) =122a(4) =217a(5) =354a(6) =543a(7) =795a(8) =1122a(9) =1537a(10) =2054a(11) =2688a(12) =3455a(13) =4372a(14) =5457a(15) =6729a(16) =8208a(17) =9915a(18) =11872a(19) =14102a(20) =16629a(21) =19478a(22) =22675a(23) =26247a(24) =30222a(25) =34629a(26) =39498a(27) =44860a(28) =50747a(29) =57192