Number of 2-compositions of n having no column with equal entries. 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.
A181301
Number of 2-compositions of n having no column with equal entries. 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) =1a(1) =2a(2) =6a(3) =20a(4) =64a(5) =206a(6) =662a(7) =2128a(8) =6840a(9) =21986a(10) =70670a(11) =227156a(12) =730152a(13) =2346942a(14) =7543822a(15) =24248256a(16) =77941648a(17) =250529378a(18) =805281526a(19) =2588432308a(20) =8320049072a(21) =26743297998a(22) =85961510758a(23) =276307781200a(24) =888141556360
External references
- oeis: A181301