Number of even entries in the top rows of 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.
A181337
Number of even entries in the top rows of 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) =1a(2) =6a(3) =28a(4) =123a(5) =512a(6) =2064a(7) =8124a(8) =31416a(9) =119820a(10) =451972a(11) =1689532a(12) =6268276a(13) =23107836a(14) =84721796a(15) =309151932a(16) =1123431812a(17) =4067533244a(18) =14679173444a(19) =52821023932a(20) =189571527236a(21) =678748381372
External references
- oeis: A181337