Number of sequences of n integers p(i) i=0..n-1 with 0<=p(i)<=2*i and -2<p(i)-p(i-1)<=2.
A180907
Number of sequences of n integers p(i) i=0..n-1 with 0<=p(i)<=2*i and -2<p(i)-p(i-1)<=2.
Terms
- a(0) =1a(1) =3a(2) =11a(3) =42a(4) =163a(5) =639a(6) =2520a(7) =9976a(8) =39595a(9) =157441a(10) =626859a(11) =2498318a(12) =9964308a(13) =39764292a(14) =158756360a(15) =634044576a(16) =2532959099a(17) =10121210373a(18) =40449588625a(19) =161680869046a(20) =646330342699
External references
- oeis: A180907