100800

Appears in sequences

• a(n) = (2*n)!*(2*n+1)! / n!^2.at n=3A000909
• Denominator of Sum_{i+j+k=n; i,j,k > 0} 1/(i*j*k).at n=9A002546
• a(n) = binomial(n,floor(n/2))*(n+1)!.at n=6A002867
• Expansion of theta series of {E_7}* lattice in powers of q^(1/2).at n=55A003781
• Bishops on an n X n board (see Robinson paper for details).at n=15A005633
• Theta series of the coset of the E_7 lattice in its dual.at n=13A005931
• a(n+1) = (n-1)*a(n) + n*n!.at n=6A006157
• Triangle of coefficients in expansion of D^n (sec x) / sec x in powers of tan x.at n=23A008294
• Numbers k such that sigma(k) >= 4*k.at n=13A023198
• Nonzero coefficients in theta series of {E_7}* lattice.at n=27A030443
• Theta series of lattice D3 tensor D3* (dimension 9, det. 262144, min. norm 6).at n=27A033694
• Expansion of e.g.f. 1/((1-x)^2*(1-x^2)).at n=7A052618
• E.g.f. (1-x^2)/(1-2x-x^2).at n=6A052622
• E.g.f. (1-2x)/(1-2x-x^3).at n=7A052639
• Expansion of e.g.f. (1 - 2*x - sqrt(1-4*x))^2 * (1 - sqrt(1-4*x))/8.at n=7A052722
• Sum of divisors of those numbers n such that n and n+1 have the same sum of divisors.at n=17A053215
• Triangle T(n,k) read by rows: number of labeled trees with n nodes and k leaves, n >= 2, 2 <= k <= n.at n=22A055314
• Number of labeled trees with n nodes and 3 leaves.at n=4A055315
• Number of square divisors of n!.at n=43A055993
• Least number whose number of divisors is n-th term from A014613 (numbers of form p*q*r*s, products of exactly 4 primes, counted with multiplicity).at n=13A061218