27343888

Appears in sequences

• Number of dissections of a polygon: binomial(4*n, n)/(3*n + 1).at n=10A002293
• Length of lists created by n substitutions k -> Range[k+1,1,-3] starting with {1}, counting down from k+1 to 1 step -3.at n=29A084080
• a(3n+k) = (k+1)*binomial(4n+k, n)/(3n+k+1), where k is n reduced mod 3.at n=30A124753
• Triangle T(n,m) read by rows, obtained from [A(x)]^m = Sum_{n>=m} T(n,m)*x^n, where A(x) (the g.f. for A069271) satisfies 2*x^2*A(x)^3 = 1 - 2*x*A(x) - sqrt(1-4*x*A(x)).at n=56A188108
• a(n) = binomial(8*n, 2*n) / (6*n + 1).at n=5A235536
• Expansion of g.f. A(x) satisfying A(x) = 1 + x*(3*A(x)^2 + A(-x)^2)/4.at n=20A369082
• Number of achiral polyominoes composed of n pentagonal cells of the hyperbolic regular tiling with Schläfli symbol {5,oo}.at n=19A369472