Number of columns with top entry equal to bottom entry in all the 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.
A181300
Number of columns with top entry equal to bottom entry in all the 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) =0a(2) =1a(3) =4a(4) =19a(5) =80a(6) =328a(7) =1304a(8) =5084a(9) =19512a(10) =73976a(11) =277688a(12) =1033848a(13) =3822584a(14) =14050824a(15) =51385720a(16) =187095240a(17) =678570360a(18) =2452626312a(19) =8837584248a(20) =31756892552a(21) =113831195000a(22) =407102551688
External references
- oeis: A181300