61542

Appears in sequences

• a(n) = [ C(2n,n)/n^2 ].at n=12A024500
• a(n) = (binomial(2*p,p)-2)/p^2 where p = prime(n).at n=5A060842
• Diagonal in array of n-gonal numbers A081422.at n=38A081438
• Expansion of (1/3)*(1 - (1-9*x-9*x^2)^(1/3)).at n=7A180399
• Number of length n+5 0..2 arrays with at most one downstep in every 5 consecutive neighbor pairs.at n=7A255104
• a(n) = (1/n^2) * Sum_{d|n} moebius(n/d)*binomial(2*d,d).at n=12A268619