690690

Appears in sequences

• a(n) = binomial(3*n+1,n)/(n+1).at n=9A006013
• a(n) = floor( binomial(n,9)/10 ).at n=28A011846
• Number of aperiodic necklaces of n beads of 2 colors, 10 of them black.at n=18A032168
• Number of necklaces with 10 black beads and n-10 white beads.at n=19A032195
• Duplicate of A006013.at n=9A046648
• Triangle of rooted planar maps, read by rows.at n=54A046652
• If n = 2*m then a(n) = binomial(3*m, m)/(2*m+1), if n=2*m+1 then a(n) = binomial(3*m+1, m+1)/(2*m+1).at n=19A047749
• Triangle read by rows in which row n contains first n numbers with exactly n distinct prime factors.at n=23A048692
• GCD of n-th primorial number and its totient.at n=16A058250
• a(n) = lcm(1,...,n) - (product of primes <= n).at n=15A068510
• Distinct values of A058250; these terms appear first at subscripts listed in A071349.at n=7A071350
• a(n) = binomial(prime(n),n)/prime(n) where prime(n) = n-th prime.at n=9A075872
• Largest squarefree number that divides A077175(n).at n=6A077176
• Smallest number beginning with 6 and having exactly n distinct prime divisors.at n=6A077331
• Integers n for which the ratio phi(n)/pi(n) is smaller than for any subsequent n. Here phi(n) is Euler's totient function and pi(n) is the number of primes that are at most n.at n=31A080289
• Geometric mean of n-th row of A080504.at n=15A080506
• 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=45A091665
• Triangle read by rows: T(n,k) is the number of noncrossing trees with root degree equal to k.at n=45A092276
• Largest squarefree number that divides A101177(n).at n=6A101178
• Smallest number beginning with 6 that is the product of exactly n distinct primes.at n=6A106416