38240

Appears in sequences

• Numbers k such that sigma_2(k)*sigma_1(k)/sigma_0(k) is a perfect square.at n=13A152218
• Constant term of the reduction by x^2 -> x+1 of the polynomial p(n,x) defined below in Comments.at n=16A192421
• Number of (n+1)X(3+1) 0..1 arrays x(i,j) with row sums sum{j*x(i,j), j=1..3+1} nondecreasing, and column sums sum{i^2*x(i,j), i=1..n+1} nondecreasing.at n=5A233362
• T(n,k) is the number of (n+1) X (k+1) 0..1 arrays x(i,j) with row sums sum{j*x(i,j), j=1..k+1} nondecreasing, and column sums sum{i^2*x(i,j), i=1..n+1} nondecreasing.at n=33A233366
• Number of (6+1)X(n+1) 0..1 arrays x(i,j) with row sums sum{j*x(i,j), j=1..n+1} nondecreasing, and column sums sum{i^2*x(i,j), i=1..6+1} nondecreasing.at n=2A233371
• Regular triangle read by rows: T(n, k) = sum(i=0, n, sum(j=k, n, 3*(-1)^(k+j)*binomial(2*k,k)*binomial(j,i)*binomial(n,i)*binomial(i,n-j)/(2*(2*i-1)*(2*j+1)*(2*n-2*i-1)))).at n=27A262886
• E.g.f.: Log( Sum_{n>=0} (n + y)^(2*n) * x^n/n! ) = Sum_{n>=1} Sum_{k=0..n+1} T(n,k) * x^n*y^k/n!, as a triangle of coefficients T(n,k) read by rows.at n=15A266521
• Number of perfect matchings on a triangular lattice of width 4 and length n.at n=9A309117
• Expansion of the o.g.f. (1 + 8*x + 10*x^2 + 8*x^3 + x^4)/((1 - x)^4*(1 + x)^2).at n=31A342362