4363921

Appears in sequences

• Number of perfect matchings (or domino tilings) in K_4 X P_n.at n=9A003769
• Area of n-th triple of squares around a triangle.at n=10A005386
• Expansion of g.f. (1-x^2)/(1-x-2*x^2+x^3).at n=27A028495
• Row sums of triangle A060556.at n=13A060557
• Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0), ending on the vertical axis and consisting of n steps taken from {(-1, -1), (0, -1), (0, 1), (1, 0), (1, 1)}.at n=13A151444
• Number of n X 2 arrays of occupancy after each element stays put or moves to some horizontal, vertical or antidiagonal neighbor.at n=6A221162
• T(n,k)=Number of nXk arrays of occupancy after each element stays put or moves to some horizontal, vertical or antidiagonal neighbor.at n=29A221165
• T(n,k)=Number of nXk arrays of occupancy after each element stays put or moves to some horizontal, vertical or antidiagonal neighbor.at n=34A221165
• Numbers k such that concat(k, d(k)) and concat(d(k), k) are both prime, where d(k) is the number of divisors of k.at n=26A284643