18091

Appears in sequences

• Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 27 ones.at n=8A031795
• Composite numbers whose divisors (except 1) all contain the digit 9.at n=33A062680
• Number of ways to place zero or more nonadjacent 0,0 1,0 2,0 3,1 4,1 5,2 6,2 7,2 polyhexes in any orientation on a planar nXnXn triangular grid.at n=7A155401
• Partial sums of A007694.at n=40A174030
• Numbers k such that k and k-1 both first appear in the same power of 2 (in base 10).at n=45A322919
• G.f. A(x) satisfies A(x) = 1/( (1-x)^2 * (1 - x*A(x) - 2*x^2*A'(x)) ).at n=5A386263