568750

Appears in sequences

• Expansion of 1/((1+5*x)*(1-15*x)).at n=5A053537
• Number of nX3 0..3 arrays with exactly floor(nX3/2) elements unequal to at least one horizontal, vertical or antidiagonal neighbor, with new values introduced in row major 0..3 order.at n=8A222661
• G.f. A(x) satisfies: Sum_{k=0..n} [x^k] A(x)^n = binomial(7*n,3*n).at n=4A244654
• Triangular array read by rows: row n shows the coefficients of the polynomial p(x,n) constructed as in Comments; these polynomials form a strong divisibility sequence.at n=32A327322