Number of (w,x,y,z) with all terms in {0,...,n} and at least one of them is the range of {w,x,y,z}.

Terms

a(0) =1a(1) =15a(2) =79a(3) =225a(4) =529a(5) =975a(6) =1711a(7) =2625a(8) =3985a(9) =5535a(10) =7711a(11) =10065a(12) =13249a(13) =16575a(14) =20959a(15) =25425a(16) =31201a(17) =36975a(18) =44335a(19) =51585a(20) =60721a(21) =69615a(22) =80719a(23) =91425a(24) =104689a(25) =117375a(26) =132991a(27) =147825a(28) =165985a(29) =183135