56160

Appears in sequences

• a(n) = 9*a(n - 1) - a(n - 2) for n>1, a(0)=0, a(1)=1.at n=6A018913
• Schoenheim bound L_1(n,7,6).at n=21A036834
• Number of double-free subsets of {1, 2, ..., n}.at n=19A050291
• Sum of divisors of those numbers n such that n and n+1 have the same sum of divisors.at n=15A053215
• Numbers n such that sigma(n)^2 > 9*sigma_2(n) where sigma_2(n) is the sum of squares over the divisors of n.at n=33A068378
• Location of records in A099564.at n=17A099565
• a(n) = A130179(n)/81.at n=34A130085
• Smallest integer k such that k or one of its left substrings (or prefixes, regarded as an integer) is divisible by any integer from {1,2,...,n}.at n=16A169858
• Smallest integer k such that k or one of its left substrings (or prefixes, regarded as an integer) is divisible by any integer from {1,2,...,n}.at n=17A169858
• A product triangle sequence based on recursion:a=4; f(n,a)=(2*a+1)*f(n-1,a)+f(n-2,a).at n=22A173005
• A product triangle sequence based on recursion:a=4; f(n,a)=(2*a+1)*f(n-1,a)+f(n-2,a).at n=26A173005
• a(n) is the number of solutions to the congruence Sum_{k=1..n} x_k == 1 (mod 2n), where x_k are distinct elements of the set {0, 1, ..., 2n}, k = 1..n.at n=5A174663
• a(n) = smallest positive even integer k such that k or one of its left substrings is divisible by any integer from {1..n}.at n=16A175516
• a(n) = smallest positive even integer k such that k or one of its left substrings is divisible by any integer from {1..n}.at n=17A175516
• Perfex numbers: n = binary XOR of divisors of n.at n=7A178911
• Irregular triangle read by rows: coefficients in order of decreasing exponents of polynomials P_g(x) related to Hultman numbers.at n=14A185259
• Numbers with prime factorization pqr^3s^5.at n=2A190475
• Number of n X 6 0..1 arrays avoiding 0 0 0 and 1 1 1 horizontally and 0 0 1 and 1 0 1 vertically.at n=12A208377
• Number of (w,x,y,z) with all terms in {1,...,n} and w<=2x and y>=3z.at n=26A212515
• Positive numbers differing from next 3 greater squares by squares.at n=7A218487