Number of ways to select 3 or more collinear points from a 4 X n grid.

Terms

a(0) =5a(1) =10a(2) =23a(3) =54a(4) =117a(5) =240a(6) =497a(7) =1006a(8) =2027a(9) =4074a(10) =8169a(11) =16356a(12) =32741a(13) =65506a(14) =131039a(15) =262110a(16) =524253a(17) =1048536a(18) =2097113a(19) =4194262a(20) =8388563a(21) =16777170a(22) =33554385a(23) =67108812a(24) =134217677a(25) =268435402a(26) =536870855a(27) =1073741766a(28) =2147483589a(29) =4294967232