21496

Appears in sequences

• Certain subgraphs of a directed graph.at n=4A005330
• Expansion of exp(tan(x)/exp(x)).at n=9A009255
• Number of disconnected labeled digraphs with n nodes.at n=4A054593
• Interprimes which are of the form s*prime, s=8.at n=32A075283
• Least k>1 such that p^k - p^(k-1) - 1 is prime for p = prime(n).at n=22A122396
• Numbers n such that gcd(n, phi(n)) = gcd(phi(n), sigma(n)) = gcd(sigma(n), n) = tau(n).at n=38A217301
• Numbers of espalier polycubes of a given volume in dimension 5.at n=23A229925
• Number of partitions of n containing the number of distinct parts as a part.at n=42A239945
• Triangle read by rows: coefficients xi(n,k) arising from the study of completely transitive graphs on n nodes.at n=16A259971
• Number of length-n binary words w such that ww is rich.at n=19A306314
• The number of connected weighted cubic graphs with weight n on 6 vertices.at n=27A321306
• Number of compositions of n with no part circularly followed by a divisor or a multiple.at n=32A328599
• Numbers m such that sigma(m) = tau(m)! where sigma(k) = A000203(k) and tau(k) = A000005(k).at n=4A351866
• Expansion of g.f. A(x,y) satisfying 0 = Sum_{n=-oo..+oo} x^n * A(x,y)^n * (y - x^(n-1))^(n+1), as a triangle of coefficients T(n,k) of x^n*y^k in A(x,y), read by rows n >= 0.at n=59A366730