2217608250

Appears in sequences

• a(n) = binomial(2*n-1, n) - binomial(2*n-1, n+3).at n=17A026016
• a(n) = T(n, [n/2]), where T is the array defined in A026009.at n=35A026021
• Expansion of (1+x^2*C^4)*C, where C = (1 - sqrt(1-4*x))/(2*x) is g.f. for Catalan numbers, A000108.at n=18A071725