1595620

Appears in sequences

• Start with Pascal's triangle; a(n) is the sum of the numbers on the periphery of the n-th central rhombus containing exactly 4 numbers.at n=10A081496
• G.f. satisfies: A(x) = (1+x*A(x)^2)*(1+x^2*A(x)^2)*(1+x^3*A(x)^2).at n=11A211854