2027025

Appears in sequences

• Double factorial of odd numbers: a(n) = (2*n-1)!! = 1*3*5*...*(2*n-1).at n=8A001147
• Triangle of coefficients of Bessel polynomials (exponents in decreasing order).at n=36A001497
• Triangle of coefficients of Bessel polynomials (exponents in decreasing order).at n=37A001497
• Triangle a(n,k) (n >= 0, 0 <= k <= n) of coefficients of Bessel polynomials y_n(x) (exponents in increasing order).at n=43A001498
• Triangle a(n,k) (n >= 0, 0 <= k <= n) of coefficients of Bessel polynomials y_n(x) (exponents in increasing order).at n=44A001498
• n-phi-torial, or phi-torial of n: Product k, 1 <= k <= n, k relatively prime to n.at n=15A001783
• Double factorials n!!: a(n) = n*a(n-2) for n > 1, a(0) = a(1) = 1.at n=15A006882
• Smallest k such that k*n is a double factorial.at n=16A007919
• Triangle of coefficients in expansion of (x+1)*(x+3)*...*(x + 2n - 1) in rising powers of x.at n=36A028338
• The convolution matrix of the double factorial of odd numbers (A001147).at n=28A035342
• Triangle of coefficients in expansion of (x-1)*(x-3)*(x-5)*...*(x-(2*n-1)).at n=36A039757
• Triangle of B-analogs of Stirling numbers of first kind.at n=44A039758
• Denominators in expansion of exp(2x)/(1-x).at n=13A053485
• Highly composite odd numbers: odd numbers where d(n) increases to a record.at n=22A053624
• Triangle T(n,k) giving number of rooted maps regardless of genus with n edges and k nodes (n >= 0, k = 1..n+1).at n=36A053979
• 2-adic factorial function.at n=16A055634
• Triangle T(m,s), m >= 0, 0 <= s <= m, arising in the computation of certain integrals.at n=36A059366
• Square array read by antidiagonals downwards: T(n,k) = (n*k)!/(k!^n*n!), (n>=1, k>=1), the number of ways of dividing nk labeled items into n unlabeled boxes with k items in each box.at n=43A060540
• Volume of n-dimensional sphere of radius r is V_n*r^n = Pi^(n/2)*r^n/(n/2)! = C_n*Pi^floor(n/2)*r^n; sequence gives denominator of C_n.at n=15A072346
• Surface area of n-dimensional sphere of radius r is n*V_n*r^(n-1) = n*Pi^(n/2)*r^(n-1)/(n/2)! = S_n*Pi^floor(n/2)*r^(n-1); sequence gives denominator of S_n.at n=17A072479