18080

Appears in sequences

• Generalized Catalan Numbers x^3*A(x)^2 + (x-1)*A(x) + 1 =0.at n=16A023431
• a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ... + a(n-3)*a(3) for n >= 4, with initial terms 1, 0, 1, 1.at n=18A025246
• a(n) = T(n,n-3), where T is the array in A026386.at n=31A026394
• Numbers n such that n divides the (right) concatenation of all numbers <= n written in base 23 (most significant digit on right).at n=15A029516
• Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 67.at n=31A031565
• a(n) in base 15 is a repdigit.at n=47A048339
• a(n) = Sum_{k=1..n} lcm(n,k).at n=39A051193
• Expansion of 1/(1 - 2*x^3 - x^4).at n=33A052922
• Numbers k such that sopf(k) = sopf(k+3), where sopf(k) = A008472(k).at n=21A063969
• First of triples of consecutive happy numbers, i.e., the first of three consecutive integers each of which is a happy number (A007770).at n=19A072494
• a(n) = round( (sqrt n)^(sqrt n) ).at n=31A094054
• a(n) = floor(sqrt(n)^sqrt(n)).at n=31A094092
• Triangle read by rows: T(n,k) is the number of 0-1-2 trees (i.e., ordered trees with all vertices of outdegree at most two) with n edges and k pairs of adjacent vertices of outdegree 2.at n=51A126218
• Sums of Pythagorean sextuples in increasing order: The sums of sets of six natural numbers which correspond to the lengths of the edges of a tetrahedron whose four faces are all different Pythagorean triangles.at n=32A248548
• Number of 4 X n 0..1 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.at n=11A281208
• Number of n X 2 0..1 arrays with each 1 adjacent to 1, 3 or 4 king-move neighboring 1s.at n=9A296798
• a(n) = ceiling(a(n-1)/(2^(1/3)-1)+1), a(1)=1.at n=7A303647
• Triangle read by rows: T(n,k) is the number of unoriented colorings of the facets of a regular n-dimensional orthotope using exactly k colors. Row n has 2n columns.at n=34A325009
• The sixth moments of the squared binomial coefficients; a(n) = Sum_{m=0..n} m^6*binomial(n, m)^2.at n=4A329444
• a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/2)} binomial(n-k,k) * a(n-2*k-1).at n=12A352864