18420

Appears in sequences

• Minimal positive solution z of Pell equation z^2 - A077426(n)*t^2 = -4.at n=39A078356
• Total number of edges in all rooted trees on n nodes.at n=10A095350
• Triangle read by rows: T(n,k) is the number of noncrossing trees with n edges and k leaves at level 1.at n=47A101371
• a(n) = 3*a(n-1) - 2*a(n-2) with a(0)=24 and a(1)=60.at n=9A182464
• Number of (n+1) X 3 0..1 arrays with the number of rightwards and downwards edge increases in each 2 X 2 subblock differing from the number in all its horizontal and vertical neighbors.at n=13A205066
• Numbers k such that 2^k + 33 is prime.at n=30A247953
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 931", based on the 5-celled von Neumann neighborhood.at n=23A273790
• Number of nX6 0..1 arrays with every element equal to 0, 1, 3 or 4 king-move adjacent elements, with upper left element zero.at n=8A297905
• Expansion of Product_{k>0} theta_3(q^k)/theta_4(q^k), where theta_3() and theta_4() are the Jacobi theta functions.at n=11A320967
• Numbers k such that prime(k) is the hypotenuse of a Pythagorean triple where one leg is also prime.at n=24A342583
• Number of ternary paths of length 3*n having exactly 2 hills.at n=9A374836
• Antidiagonal sums of A343052.at n=47A379703
• Array read by antidiagonals: T(n,k) is the number of nonequivalent essentially parallel series-parallel networks with longest path of at most n edges and largest cut set of at most k edges.at n=31A391485