Number of columns with an odd sum in all 2-compositions of n. A 2-composition of n is a nonnegative matrix with two rows, such that each column has at least one nonzero entry and whose entries sum up to n.
A181326
Number of columns with an odd sum in all 2-compositions of n. A 2-composition of n is a nonnegative matrix with two rows, such that each column has at least one nonzero entry and whose entries sum up to n.
Terms
- a(0) =0a(1) =2a(2) =8a(3) =40a(4) =168a(5) =696a(6) =2776a(7) =10864a(8) =41800a(9) =158816a(10) =597176a(11) =2226512a(12) =8242344a(13) =30328160a(14) =111013784a(15) =404518640a(16) =1468154504a(17) =5309771264a(18) =19143323000a(19) =68823556368a(20) =246805713000a(21) =883028659744
External references
- oeis: A181326