21256

Appears in sequences

• Number of partially labeled rooted trees with n nodes (4 of which are labeled).at n=3A000525
• Triangle read by rows: T(n,k) is the number of partially labeled rooted trees with n vertices, k of which are labeled, 0 <= k <= n.at n=32A008295
• Number of ordered positive integer solutions (m_1, m_2, ..., m_k) (for some k) to Sum_{i=1..k} m_i=n with |m_i-m_{i-1}| <= 1 for i = 2 ... k.at n=20A034297
• Number of cycles for vectors of length n under the Ducci map.at n=36A135547
• a(n) = number of triples (a,b,c) of natural numbers a,b,c <= n with gcd(a,b)=gcd(b,c)=gcd(c,a)=1.at n=41A256390
• Numbers k that end with ( sum of digits of k )^2.at n=30A270343
• Number T(n,k) of set partitions of [n] such that the maximal value of all absolute differences between least elements of consecutive blocks and between consecutive elements within the blocks equals k; triangle T(n,k), n>=0, 0<=k<=max(n-1,0), read by rows.at n=50A287416
• Positive integers that have exactly ten representations of the form 1 + p1 * (1 + p2* ... * (1 + p_j)...), where [p1, ..., p_j] is a (possibly empty) list of distinct primes.at n=18A317400
• Expansion of Product_{i>=1, j>=1, k>=1} (1 - x^(i*j*k))/(1 + x^(i*j*k)).at n=33A321241
• Number of ways to choose 3 points that form an equilateral triangle from the A001845(n) points in a regular octahedral grid of size n.at n=7A342353
• Numbers k such that the k-th composition in standard order is an alternating permutation of {1..k} for some k.at n=42A349051
• a(n) is the number of distinct five-cuboid combinations that fill an n X n X n with only strict cuboids.at n=17A386902