27783

Appears in sequences

• Numbers of the form 3^i*7^j with i, j >= 0.at n=32A003594
• Numbers of form 7^i*9^j, with i, j >= 0.at n=17A025631
• Number of Hamiltonian cycles in the directed graph with 2n nodes {0..2n-1} and edges from each i to 2i (mod 2n) and to 2i+1 (mod 2n).at n=20A027362
• Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 21 ones.at n=16A031789
• Numbers whose prime factors are 3 and 7.at n=17A033850
• a(1)=8; if n = Product p_i^e_i, n > 1, then a(n) = Product p_{i+1}^{e_i+2}.at n=19A045971
• Odd numbers divisible by exactly 7 primes (counted with multiplicity).at n=27A046320
• a(n) = n*(n+1)*(n^2+5*n+18)/24.at n=26A051744
• Numbers n such that n | 8^n + 7^n + 6^n.at n=40A057233
• Numbers n such that n | 12^n + 11^n + 10^n + 9^n + 8^n + 7^n + 6^n + 5^n + 4^n.at n=43A057285
• Numbers k such that k | 11^k + 10^k + 9^k + 8^k + 7^k + 6^k + 5^k + 4^k + 3^k.at n=42A057286
• Numbers k such that phi(k) and sigma(k) are both perfect squares.at n=16A067781
• Numbers n such that sopf(sigma(n)) = sigma(sopf(n)), where sopf(x) = sum of the distinct prime factors of x.at n=36A076532
• a(n) = 3*n^3.at n=21A117642
• Number of n X n symmetric binary matrices with every element adjacent horizontally (and vertically) to some 0.at n=6A140419
• Products of the 4th power of a prime and a distinct prime of power 3 (p^4*q^3).at n=9A179666
• a(n) = product of non-powerful divisors d of n.at n=62A183103
• a(n) = product of divisors of n that are not perfect powers.at n=62A183105
• q-expansion of modular form psi_0^6/t_{3B}^2.at n=16A198958
• Least term of A094179 with exactly 2n divisors.at n=9A204046