Number of (w,x,y,z) with all terms in {1,...,n} and |w-x| >= w + |y-z|.

Terms

a(0) =0a(1) =0a(2) =2a(3) =10a(4) =32a(5) =78a(6) =162a(7) =300a(8) =512a(9) =820a(10) =1250a(11) =1830a(12) =2592a(13) =3570a(14) =4802a(15) =6328a(16) =8192a(17) =10440a(18) =13122a(19) =16290a(20) =20000a(21) =24310a(22) =29282a(23) =34980a(24) =41472a(25) =48828a(26) =57122a(27) =66430a(28) =76832a(29) =88410