20925

Appears in sequences

• Odd numbers k that divide phi(k)*sigma(k).at n=19A015706
• Numbers k such that (68*10^(k-1) + 13)/9 is a depression prime.at n=13A082713
• Solution to the non-squashing boxes problem (version 1).at n=38A089054
• Triangle read by rows: T(n,k) is the number of ternary trees with n edges and having k vertices of outdegree 2 (n >= 0, k >= 0).at n=20A120982
• Number of ternary trees with n edges and having no vertices of degree 2. A ternary tree is a rooted tree in which each vertex has at most three children and each child of a vertex is designated as its left or middle or right child.at n=8A120985
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, -1), (-1, 0, 0), (-1, 0, 1), (0, -1, 0), (1, 1, 0)}.at n=9A149234
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 1), (-1, 0, 0), (0, 0, -1), (1, 0, -1), (1, 1, 1)}.at n=8A149682
• Row sums of triangle A159924.at n=6A159925
• Expansion of (1 + 14*x) / ((1 - x)*(1 - 2*x)*(1 - 4*x)*(1 - 8*x)*(1 - 16*x)).at n=3A177728
• Expansion of (1-4*x+7*x^2-5*x^3+4*x^4-6*x^5+21*x^6+18*x^7-5*x^8)/(1-x)^5.at n=15A212393
• Number of partitions p of n such that max(p)-min(p) = 7.at n=45A218570
• Numbers with the property that in their factorization over distinct terms of A050376, the sums of prime and nonprime terms of A050376 are equal.at n=22A241270
• Sum_{i=1..n} Sum_{j=1..n} (i OR j), where OR is the binary logical OR operator.at n=30A258438
• Numbers of the form A000217(n)*A007494(n) that are divisible by 3.at n=25A295867
• Numbers whose numerator and denominator of the harmonic mean of their divisors are both 5-smooth numbers.at n=49A348868
• Irregular table read by rows: T(n,k) is the number of k-gons, k>=2, among all distinct circles that can be constructed from the 3 vertices and the equally spaced 3*n points placed on the sides of an equilateral triangle, using only a compass.at n=42A372617
• Odd binary Niven numbers (A144302) k such that k/wt(k) is also an odd binary Niven number, where wt(k) = A000120(k) is the binary weight of k.at n=42A376618