Number of length n 0..3 arrays with new values introduced in order from both ends.

A245158

Number of length n 0..3 arrays with new values introduced in order from both ends.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =4a(4) =9a(5) =23a(6) =65a(7) =199a(8) =653a(9) =2275a(10) =8313a(11) =31439a(12) =121637a(13) =477307a(14) =1888721a(15) =7509799a(16) =29940861a(17) =119550419a(18) =477742889a(19) =1909988479a(20) =7637856725a(21) =30546970411a(22) =122178444417a(23) =488693854679

External references