23256

Appears in sequences

• Coefficient of x^5 in expansion of (1 + x + x^2)^n.at n=15A000574
• If F(n) is the n-th Fibonacci number, then a(2n) = (F(2n+1) + F(n+2))/2 and a(2n+1) = (F(2n+2) + F(n+1))/2.at n=22A001224
• a(n) = 9*binomial(2n,n-4)/(n+5).at n=6A001392
• Number of permutations of [n+1] with exactly 1 increasing subsequence of length 3.at n=7A003517
• Alkane (or paraffin) numbers l(7,n).at n=30A005994
• From the enumeration of corners.at n=8A006332
• a(n) = floor(n*(n-1)*(n-2)*(n-3)/5).at n=20A011915
• a(n) = lcm(n, Fibonacci(n)).at n=17A014965
• Fibonacci sequence beginning 0, 9.at n=18A022092
• Theta series of A_18 lattice.at n=2A023909
• Theta series of A*_18 lattice.at n=35A023930
• Theta series of A*_18 lattice.at n=38A023930
• a(n) = (1/2)*s(n+3), where s = A025251.at n=16A025252
• a(n) = Sum_{i=0..n} Sum_{j=i..2*i} A027052(i, j).at n=10A027068
• a(n) = n*(n+1)*(n+2)*(n+3)/4.at n=16A033487
• Triangle formed from odd-numbered columns of triangle of expansions of powers of x in terms of Chebyshev polynomials U_n(x). Sometimes called Catalan's triangle.at n=47A039598
• a(n) is the number of nonseparable planar maps with 2*n+1 edges and a fixed outer face of 4 edges which are invariant under a rotation of a 1/2 turn. (Column 2 of A091665.)at n=6A046649
• Triangle of rooted planar maps, read by rows.at n=34A046652
• a(n)=Sum{T(2i,n-2i): i=0,1,...,[ n/2 ]}, array T as in A049600.at n=12A049601
• Triangle T(n,k), k>=0 and n>=1, read by rows defined by: T(n,k) = (2k+3)*binomial(2n,n-k-1)/(n+k+2).at n=48A050155