20544

Appears in sequences

• G.f.: (1 + x^4 + x^7 + 2*x^8 + x^9 + x^12 + x^16)/Product_{i=1..8} (1 - x^i).at n=37A003405
• Number of tournaments on n nodes with a unique winner.at n=5A013976
• a(n) = position of 3*n^3 in A003072.at n=39A024970
• a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ... + a(n-3)*a(3) for n >= 4, with initial terms 1, 2, 1, 1.at n=14A025243
• 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 71.at n=37A031569
• Triangle read by rows: number of 0-1-2 trees (i.e., ordered trees with vertices of outdegrees 0, 1, or 2) with n edges and exactly k vertices that have 2 children, both being leaves (n >= 0, 0 <= k <= floor((n+2)/4)).at n=34A126191
• Lower triangular array, called S1hat(-4), related to partition number array A145369.at n=58A145370
• a(0)=4; a(n)=n^2+a(n-1) for n>0.at n=39A153058
• Triangle read by rows: T(n,k) is the number of peakless Motzkin paths of length n having k UHD's; here U=(1,1), H=(1,0), and D=(1,-1).at n=53A190172
• T(n,k) gives the number of permutations of the set [n] that contain k occurrences of the subword (132); irregular array read by rows (n >= 0 and 0 <= k <= max(0, floor((n-1)/2))).at n=18A197365
• Number of 2-packed matrices with exactly n nonzero entries.at n=5A230880
• Number of partitions of n with difference -5 between the number of odd parts and the number of even parts, both counted without multiplicity.at n=45A242687
• Number of permutations of [n] containing exactly one occurrence of the consecutive pattern 132.at n=5A263885
• Triangle read by rows: T(n,k) is the number of bargraphs of semiperimeter n having k levels. A level in a bargraph is a maximal sequence of two or more adjacent horizontal steps; it is preceded and followed by either an up step or a down step.at n=41A273344
• Decimal representation of the diagonal from the corner to the origin of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 390", based on the 5-celled von Neumann neighborhood.at n=34A287981
• Decimal representation of the diagonal from the corner to the origin of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 390", based on the 5-celled von Neumann neighborhood.at n=35A287981
• Take apart the sides of each of the integer-sided scalene triangles with perimeter n (at their vertices) and rearrange them orthogonally in 3-space so that their endpoints coincide at a single point. a(n) is the total surface area of all rectangular prisms enclosed in this way.at n=36A308235
• Numbers k such that k divides sum of k-th twin prime pair.at n=33A335303
• Number of permutations of symmetric group S_n with an odd number of cycles of length 2 or more.at n=8A373340
• Triangle T(n, k) for the number of permutations of symmetric group S_n with an odd number of non-fixed point cycles, without k <= n particular fixed points.at n=36A374420