21384

Appears in sequences

• Coordination sequence for D_4 lattice.at n=11A007900
• "DHK[ 8 ]" (bracelet, identity, unlabeled, 8 parts) transform of 1,1,1,1,...at n=14A032249
• a(n) is the number of sets of natural numbers [a,b,c,d,e] that can be produced with the numbers [0..n] such that the values of all the distinct parenthesized expressions of a-b-c-d-e are different.at n=8A054026
• Engel expansion of exp(Pi * sqrt(163)) - 262537412640768743.at n=43A076303
• Numbers k such that Omega(k) = Omega(k-1) + Omega(k-2) + Omega(k-3) + Omega(k-4) where Omega(k) denotes the number of prime factors of k, counting multiplicity.at n=21A078095
• a(n) = ceiling(((1*n^0 + 1*n^1 + 2*n^2 + 4*n^3)/(1*n^0 + 2*n^1 + 1*n^2))^2).at n=37A085505
• Triangle read by rows: T(n,k)=k^3*2^k*binomial(2n-k,n-k)/(2n-k) (1<=k<=n).at n=30A112327
• Reversible Lynch-Bell numbers.at n=25A117954
• a(n) = 4*n*(floor(n^2/2)+1). For n >= 3, this is the number of directed Hamiltonian paths on the n-prism graph.at n=22A124350
• Triangle, read by rows, where row n equals the inverse binomial transform of column n in the rectangular table A124460.at n=51A124469
• Number of (directed) Hamiltonian paths in the n-Möbius ladder graph.at n=19A137883
• Number of 4-way intersections in the interior of a regular 6n-gon.at n=32A137938
• a(n) is the smallest number m such that phi(m)+sigma(m)=n*pi(m).at n=27A145747
• a(n) = (2*n^3 + 5*n^2 - 9*n)/2.at n=26A162258
• Numbers k such that phi(tau(k)) = sopf(k).at n=30A173326
• The Wiener index of the Dutch windmill graph D(6,n) (n>=1).at n=21A180578
• Number of 4-step left-handed knight's tours (moves only out two, left one) on an n X n board summed over all starting positions.at n=27A187174
• Numbers with prime factorization pq^3r^5.at n=10A190011
• Smallest number k such that k^n is the sum of numbers in a twin prime pair.at n=10A195336
• Number of n X 4 0..1 arrays avoiding 0 0 1 and 0 1 0 horizontally and 0 0 1 and 1 0 1 vertically.at n=10A207064