27088870

Appears in sequences

• a(n) = C(1,1) + C(3,2) + C(5,3) + ... + C(2*n-1,n).at n=13A079309
• Expansion of (1+2x-sqrt(1-4x^2))/(2(1-x^2)*sqrt(1-4x^2)).at n=28A174783
• Number of base pyramids in all length n left factors of Dyck paths.at n=28A191790
• a(n) = Sum_{k=1..n-1} ((-1)^(k+n+1)*binomial(k,floor(k/2))).at n=28A332754
• Number of nonempty subsets of {1..n} with median n/2.at n=28A361801
• Number of nonempty subsets of {1..n} with median n/2.at n=29A361801