99144

Appears in sequences

• Number of 3-element ordered antichain covers of an unlabeled n-element set.at n=15A056074
• Number of rooted planar bi-Eulerian maps with 2n edges. Bi-Eulerian: all its vertices and faces are of even valency.at n=6A069726
• Binomial transform of n^2*2^n/2.at n=7A077616
• a(n) = n^4 - n^3.at n=18A085537
• a(n) = n*(n + 1)^3.at n=17A085540
• Triangle read by rows: T(n,k) = (-1)^k*3^(n-1-2k)*binomial(n-k,k)*(4n-5k)/(n-k) (0 <= k <= floor(n/2), n >= 1).at n=38A104063
• Expansion of g.f. ((1+x)/(1-3*x))^2.at n=8A113071
• a(n) = number of reverse alternating fixed-point-free involutions w on 1,2,...,2n, i.e., w(1) < w(2) > w(3) < w(4) > ... < w(2n), w^2=1 and w(i) != i for all i.at n=10A115455
• 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, 0, 0), (-1, 0, 1), (1, 0, -1), (1, 0, 1), (1, 1, 1)}.at n=8A151027
• a(n) = ((2+sqrt(3))*(3+sqrt(3))^n + (2-sqrt(3))*(3-sqrt(3))^n)/2.at n=7A162273
• Numbers with prime factorization pq^3r^6.at n=22A190467
• Triangular array read by rows: T(n,k) is the number of 2-regular labeled graphs on n nodes that have exactly k connected components (cycles); n>=3, 1<=k<=floor(n/3).at n=13A201013
• Number of (w,x,y,z) with all terms in {0,...,n}, w, x and y odd, and z odd.at n=34A212764
• G.f. A(x) satisfies: [x^k] (1+x)^(n*(n+1)/2) * A(x) = 0 for k = n*(n-1)/2 + 1 through k = n*(n+1)/2 for n >= 1.at n=14A305601
• Sum of even integers <= n times the sum of odd integers <= n.at n=35A330520
• Number of compositions of n with all adjacent parts (x, y) satisfying x >= 2y or y = 2x.at n=44A342335