a(n) is the number of 2-point antichains in the poset D_{2n+1} of type D, whose elements are compositions of 2n+1.
A344791
a(n) is the number of 2-point antichains in the poset D_{2n+1} of type D, whose elements are compositions of 2n+1.
Terms
- a(0) =2a(1) =10a(2) =29a(3) =66a(4) =129a(5) =228a(6) =374a(7) =580a(8) =860a(9) =1230a(10) =1707a(11) =2310a(12) =3059a(13) =3976a(14) =5084a(15) =6408a(16) =7974a(17) =9810a(18) =11945a(19) =14410a(20) =17237a(21) =20460a(22) =24114a(23) =28236a(24) =32864a(25) =38038a(26) =43799a(27) =50190a(28) =57255a(29) =65040
External references
- oeis: A344791