Number of (w,x,y,z) with all terms in {0,...,n} and max{w,x,y,z}>=2*min{w,x,y,z}.

Terms

a(0) =1a(1) =15a(2) =79a(3) =239a(4) =593a(5) =1199a(6) =2239a(7) =3759a(8) =6049a(9) =9119a(10) =13391a(11) =18815a(12) =25969a(13) =34719a(14) =45823a(15) =59039a(16) =75329a(17) =94319a(18) =117199a(19) =143439a(20) =174481a(21) =209615a(22) =250559a(23) =296399a(24) =349153a(25) =407679a(26) =474319a(27) =547679a(28) =630449a(29) =720959