21145

Appears in sequences

• Triangle of coefficients from fractional iteration of e^x - 1.at n=29A008826
• Number of proper partitions of a set of n labeled elements.at n=7A008827
• Numbers k such that the continued fraction for sqrt(k) has period 53.at n=30A020392
• a(n) = Sum_{i=1..n} LookAndSay(i).at n=28A079664
• Triangle T(n,k) read by rows: T(n,k) = (k-1)*T(n-1,k) + (n-k+2)*T(n-1, k-1), with T(n,1)=1, for 1 <= k <= n, n >= 1.at n=33A157011
• Positive numbers y such that y^2 is of the form x^2+(x+2401)^2 with integer x.at n=16A157247
• Expansion of g.f. (1+2*x+3*x^2)/(1-3*x-14*x^2+15*x^3+7*x^4).at n=6A177467
• Number of n X n 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 1 0 and 1 0 1 vertically.at n=4A207913
• Number of nX5 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 1 0 and 1 0 1 vertically.at n=4A207915
• T(n,k)=Number of nXk 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 1 0 and 1 0 1 vertically.at n=40A207918
• Number of 5Xn 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 1 0 and 1 0 1 vertically.at n=4A207920
• The order of the semigroup of orientation-preserving partial transformations on n elements.at n=6A289713
• Squarefree semiprimes k such that k+1 is the product of three distinct primes and k+2 is the product of four distinct primes.at n=27A376352