52164

Appears in sequences

• Number of rooted toroidal maps with 3 faces and n vertices and without separating cycles or isthmuses.at n=4A006423
• a(n) = 3!*n*S(n-1,3), where S denotes the Stirling numbers of second kind.at n=9A052761
• Numbers m for which Sum_{i=1..k} (1+1/p_i) + Product_{i=1..k} (1+1/p_i) is an integer, where p_i are the k prime factors of m (with multiplicity).at n=11A199767
• a(n) = number of n-lettered words in the alphabet {1, 2, 3} with as many occurrences of the substring (consecutive subword) [1, 1] as of [1, 2].at n=11A211276
• Triangular array read by rows. T(n,k) is the number of chain topologies on an n-set with exactly k open sets where one of the open sets is a single point set, n >= 2, 3 <= k <= n+1.at n=30A282507
• Numbers k such that k^2 + 1 is a Fermat pseudoprime to base 3.at n=5A333316
• Number of non-collinear triples in a 5 X n rectangular grid.at n=13A334707
• First elements of maximal isospectral chains of length 3.at n=6A335082
• Triangle read by rows: T(n,k) is the number of rooted toroidal maps with n edges and k faces and without separating cycles or isthmuses, n >= 2, k = 1..n-1.at n=23A343090
• Triangle read by rows: T(n,k) is the number of rooted toroidal maps with n edges and k faces and without separating cycles or isthmuses, n >= 2, k = 1..n-1.at n=25A343090
• Table read by rows: row n is the unique primitive Pythagorean triple (a,b,c) such that a = prime(n)*prime(n+1) and its long leg and hypotenuse are consecutive natural numbers.at n=16A370763
• a(n) = Sum_{k=0..n} 3^k * binomial(n+2,k) * binomial(n+2,k+2).at n=5A387339