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

Terms

a(0) =1a(1) =16a(2) =81a(3) =254a(4) =609a(5) =1234a(6) =2215a(7) =3640a(8) =5599a(9) =8182a(10) =11479a(11) =15580a(12) =20575a(13) =26554a(14) =33607a(15) =41824a(16) =51295a(17) =62110a(18) =74359a(19) =88132a(20) =103519a(21) =120610a(22) =139495a(23) =160264a(24) =183007a(25) =207814a(26) =234775a(27) =263980a(28) =295519a(29) =329482