Number of (w,x,y) with all terms in {0,...,n} and even range.

Terms

a(0) =1a(1) =2a(2) =15a(3) =28a(4) =65a(5) =102a(6) =175a(7) =248a(8) =369a(9) =490a(10) =671a(11) =852a(12) =1105a(13) =1358a(14) =1695a(15) =2032a(16) =2465a(17) =2898a(18) =3439a(19) =3980a(20) =4641a(21) =5302a(22) =6095a(23) =6888a(24) =7825a(25) =8762a(26) =9855a(27) =10948a(28) =12209a(29) =13470