639730

Appears in sequences

• a(n) = floor(binomial(n,6)/6).at n=40A011852
• a(n) = -A141055(n)/(n+1)!.at n=35A141321
• (Denominators of Cauchy numbers of the first kind c_{2n})/6.at n=17A222560
• (Denominators of Cauchy numbers of the second kind hat c_{2n})/6.at n=17A222561
• Least positive integer k such that 3^n-1 and k^n-1 are relatively prime.at n=35A268081
• a(0) = 1, a(n) = (denominator of the Bernoulli number B_{2n})/3, for n>=1.at n=18A277087
• Denominators of the generalized Bernoulli numbers B[3,1] = 3^n*B(n, 1/3).at n=36A285068
• a(n) = denominator(n!*[z^n](z*(exp(z)+2*exp(-(1/2)*z)*cos((1/2)*z* 3^(1/2)))/(1-exp(-z)))).at n=36A306149
• Smallest k for which the number of divisors d of k such that d == -d^k (mod k) is equal to n, or -1 if no such k exists.at n=10A386913