Number of ways of choosing at most n-1 items from a set of size 2*n+1.

A008549

Number of ways of choosing at most n-1 items from a set of size 2*n+1.

Terms

    a(0) =0a(1) =1a(2) =6a(3) =29a(4) =130a(5) =562a(6) =2380a(7) =9949a(8) =41226a(9) =169766a(10) =695860a(11) =2842226a(12) =11576916a(13) =47050564a(14) =190876696a(15) =773201629a(16) =3128164186a(17) =12642301534a(18) =51046844836a(19) =205954642534a(20) =830382690556

External references