18916

Appears in sequences

• Numerators of continued fraction convergents to sqrt(569).at n=6A042090
• Numbers having four 4's in base 8.at n=28A043440
• Numbers n such that 215*2^n-1 is prime.at n=24A050859
• Third row of Pascal-(1,4,1) array A081579.at n=39A081587
• Triangle T(m,k) read by rows, where T(m,k) is the number of ways in which 1 <= k <= m positions can be picked in an m X m square array such that their adjacency graph consists of a single component. Two positions (s,t), (u,v) are considered as adjacent if max(abs(s-u), abs(t-v)) <= 1.at n=32A098485
• Triangle read by rows: T(n,k) = (1/k) times the number of functions from an n-element set into but not onto a k-element set.at n=39A101031
• Number of base 26 circular n-digit numbers with adjacent digits differing by 5 or less.at n=4A125389
• a(n) = 3*3^n - 3*2^n + 1.at n=7A126644
• Triangle T(n, k) = Sum_{j=0..k-1} (-1)^j*binomial(k, j+1)*(k-j)^(n-k), read by rows.at n=57A158198
• The number of ways of partitioning the multiset {1,1,2,3,...,n-1} into exactly three nonempty parts.at n=8A168583
• Number of partitions p of n such that ceiling(mean(p)) is a part and floor(mean(p)) is not.at n=46A241341
• Triangle T(n,k): number of ways of partitioning the n-element multiset {1,1,2,3,...,n-1} into exactly k nonempty parts, n>=1 and 1<=k<=n.at n=57A241500
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 507", based on the 5-celled von Neumann neighborhood.at n=28A272587
• Compound filter: a(n) = P(A286357(n), A161942(n)), where P(n,k) is sequence A000027 used as a pairing function.at n=71A286358
• Array read by antidiagonals: T(n,k) = number of n X k lonesum decomposable (0,1) matrices.at n=57A299906
• Array read by antidiagonals: T(n,k) = number of n X k lonesum decomposable (0,1) matrices.at n=63A299906
• a(n) = Sum_{p in P} (H(2,p)^2)/2, where P is the set of partitions of n, and H(2,p) is the number of hooks of length 2 in p.at n=27A302348
• a(n) = N^(1/4) * log(N) / sqrt(log(log(N))) rounded to nearest integer, with N=2^n. Related to operation count of the deterministic factorization of an integer N using an improved Pollard-Strassen method.at n=39A309916
• Coefficient of x^n in the expansion of ( (1+x)^2 / (1-x^3)^2 )^n.at n=7A370215
• Triangle read by rows: T(n,k) is the number of embeddings on the sphere of planar graphs with n vertices and k faces having connectivity exactly 2 and minimum vertex degree at least 3, k=6..2n-5.at n=40A378077