Number of (w,x,y,z) with all terms in {0,...,n} and (least gapsize)>2.

Terms

a(0) =0a(1) =0a(2) =0a(3) =2a(4) =16a(5) =62a(6) =186a(7) =456a(8) =962a(9) =1818a(10) =3162a(11) =5156a(12) =7986a(13) =11862a(14) =17018a(15) =23712a(16) =32226a(17) =42866a(18) =55962a(19) =71868a(20) =90962a(21) =113646a(22) =140346a(23) =171512a(24) =207618a(25) =249162a(26) =296666a(27) =350676a(28) =411762a(29) =480518