18444

Appears in sequences

• Triangle of rooted planar maps, read by rows.at n=33A046652
• Number of configurations of the sliding block 8-puzzle that require a minimum of n moves to be reached, starting with the empty square in the center.at n=21A089474
• Triangle read by rows: T(n,k) is the number of nonseparable planar maps with 2*n+1 edges and a fixed outer face of 2*k edges which are invariant under a rotation of a 1/2 turn.at n=30A091665
• Numbers k such that k and k+1 have 4 distinct prime factors.at n=22A140078
• G.f. A(x) satisfies A(x/A(x)) = 1/(1-x)^6.at n=4A145170
• Number of ways to place zero or more nonadjacent 0,0 1,0 1,1 2,0 2,2 3,1 polyhexes in any orientation on a planar nXnXn triangular grid.at n=6A155250
• Fibonacci sequence beginning 29, 31.at n=14A157681
• Smallest number k such that omega(k)+ omega(k+1)+ omega(k+2)+ omega(k+3)= n.at n=12A175206
• a(n) = a(n-1) + a(n-2), for n>=2, with a(0)=27, a(1)=2.at n=16A190994
• G.f. satisfies: A(A(x)) = Sum_{n>=1} a(n)*x^n / (1-x)^(n*(n+1)/2), where g.f. A(x) = Sum_{n>=1} a(n)*x^n.at n=6A193195
• Number of (n+1) X (2+1) 0..7 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 5, with no adjacent elements equal (constant-stress tilted 1 X 1 tilings).at n=2A235206
• Number of (n+1) X (3+1) 0..7 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 5, with no adjacent elements equal (constant-stress tilted 1 X 1 tilings).at n=1A235207
• T(n,k) is the number of (n+1) X (k+1) 0..7 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 5, with no adjacent elements equal (constant-stress tilted 1 X 1 tilings).at n=7A235212
• T(n,k) is the number of (n+1) X (k+1) 0..7 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 5, with no adjacent elements equal (constant-stress tilted 1 X 1 tilings).at n=8A235212
• Number of (n+1)X(n+1) 0..1 arrays with every 2X2 subblock diagonal minus antidiagonal sum nondecreasing horizontally, vertically and ne-to-sw antidiagonally.at n=10A253428
• Number of length n arrays of permutations of 0..n-1 with each element moved by -5 to 5 places and exactly one more element moved upwards than downwards.at n=8A263761
• The chalcogen sequence (a(n) = A018227(n)-2).at n=44A271994
• Decimal representation of the x-axis, from the left edge to the origin, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 310", based on the 5-celled von Neumann neighborhood.at n=14A281037
• Expansion of Product_{k>=1} ((1 + x^k) / (1 - x^(4*k)))^k.at n=19A285458
• Numbers k such that k and k+1 each have at least 4 distinct prime factors.at n=22A321504