Number of (w,x,y,z) with all terms in {0,...,n} and distinct consecutive gap sizes.

Terms

a(0) =0a(1) =4a(2) =28a(3) =122a(4) =340a(5) =786a(6) =1558a(7) =2814a(8) =4690a(9) =7404a(10) =11130a(11) =16140a(12) =22652a(13) =30992a(14) =41416a(15) =54310a(16) =69968a(17) =88830a(18) =111234a(19) =137674a(20) =168526a(21) =204344a(22) =245542a(23) =292728a(24) =346360a(25) =407100a(26) =475444a(27) =552114a(28) =637644a(29) =732810