19664

Appears in sequences

• Number of centered 5-valent trees with n nodes.at n=17A036648
• Numbers whose base-3 representation contains exactly one 0 and no 1's.at n=34A044970
• T(n,n-2), array T as in A047120.at n=8A047124
• a(n) = 3^n - 2*n - 1.at n=9A061981
• Expansion of e.g.f. cosh(sqrt(2)*x) + exp(x)*(cosh(sqrt(2)*x) - 1).at n=12A088015
• Number of cycles in range [A014137(n-1)..A014138(n-1)] of permutation A071665/A071666.at n=13A089872
• Poincaré series [or Poincare series] P(C_{4,2}(0); t).at n=19A124637
• Recursion based on Exp[Pi/4]: a(n)=Floor[a(n-1)*Exp[Pi/4]] Angular domain {0,Pi/4} is the smallest self-similar piece of a sine wave.at n=14A136671
• Denominators of triangle T(n,k), n>=0, 0<=k<=n, read by rows: T(n,k) is the coefficient of x^(2k+1) in polynomial u_n(x), used to approximate x->sin(Pi*x)/Pi.at n=17A144847
• The LerchPhi functional part of A060187 MacMahon numbers is treated/ solved for as a curvature to give a set of polynomial triangle sequence coefficients: p(x,n) = Sum[A060187(n,m)*x^(m-1),{m,0,n}]; q(x,n)=k from Solve[FullSimplify[ExpandAll[p[x, n]/(x - 1)^n]] - (1 + k/x^2) == 0, k].at n=37A146543
• Coefficients of Pascal's triangle polynomial minus MacMahon polynomial A060187 with a power of x divided out: q(x,n)=2^n*(1 - x)^(n + 1)* LerchPhi[x, -n, 1/2]; p(x,n)=((x+1)^n-q(x,n))/x.at n=28A146568
• Sum of a positive square and a positive cube in at least three ways.at n=34A171385
• 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=26A187174
• Number of 6-element nondividing subsets of {1, 2, ..., n}.at n=27A187493
• Triangular array: the fission of ((x+2)^n) by (q(n,x)) given by q(n,x)=x^n+x^(n-1)+...+x+1.at n=43A193850
• Mirror of the triangle A193850.at n=37A193851
• The number of partitions of n which represent Chomp positions with Sprague-Grundy value 9.at n=57A284782
• Growth series for group with presentation < S, T : S^2 = T^3 = (S*T)^7 = 1 >.at n=38A298805
• Number of ways to dissect an equilateral triangle into n non-overlapping equilateral triangles counting isomorphisms only once.at n=15A299705
• Irregular triangle read by rows: coefficients of q-Eulerian polynomials of Type B.at n=25A333273