27136

Appears in sequences

• a(n) = number of (s(0), s(1), ..., s(n)) such that every s(i) is an integer, s(0) = 0, |s(i) - s(i-1)| = 1 for i = 1,2,3; |s(i) - s(i-1)| <= 1 for i >= 4, s(n) = 4. Also a(n) = T(n,n-4), where T is the array defined in A026082.at n=9A026087
• Numbers k such that the number of steps to reach 1 in '3x+1' problem equals tau(k), the number of divisors of k.at n=34A070980
• Number of permutations of {1,2,...,n} that result in a binary search tree (when elements of the permutation are inserted in that order) of height n-1 (i.e., the second largest possible height).at n=11A076616
• Structured meta-prism numbers, the n-th number from a structured n-gonal prism number sequence.at n=15A100177
• Sequence whose Hankel transform is a (1,1) Somos-4 sequence.at n=17A174013
• Numbers of the form p^9*q where p and q are distinct primes.at n=14A179692
• Triangle read by rows: T(n,k) is the number of L-convex polyominoes of semiperimeter n, having k maximal rectangles (n >= 2, 1 <= k <= floor(n/2)). An L-convex polyomino is a convex polyomino in which any two cells can be connected by a path internal to the polyomino and which has at most 1 change of direction (i.e., one of the four orientations of the letter L). A maximal rectangle in an L-convex polyomino P is a rectangle included in P that is maximal with respect to inclusion.at n=34A181368
• Number of right isosceles triangles that can be formed from the n^2 points of n X n grid of points (or geoboard).at n=15A187452
• Number of (n+1) X 3 0..1 arrays with column and row pair sums b(i,j)=a(i,j)+a(i,j-1) and c(i,j)=a(i,j)+a(i-1,j) such that rows of b(i,j) and columns of c(i,j) are lexicographically nondecreasing.at n=10A203446
• Number of n X 5 0..1 arrays avoiding 0 0 0 and 1 1 1 horizontally and 0 0 1 and 1 0 1 vertically.at n=16A208376
• Sigma(n)-n values in A085844.at n=35A216383
• Decimal representation of the x-axis, from the origin to the right edge, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 493", based on the 5-celled von Neumann neighborhood.at n=14A282659
• E.g.f.: exp((1/(1-x)^8 - 1)/8).at n=5A293987
• a(n) = A341886(n)/2; numbers k such that A307437(k) is even.at n=8A341887
• First differences of A230624.at n=49A349823
• Number of minimum dominating sets in the 2 X n king graph.at n=24A350816
• a(n) is the smallest centered triangular number with exactly n prime factors (counted with multiplicity).at n=10A358929
• Centered triangular numbers that are pseudoperfect (semiperfect).at n=8A377747
• a(n) = 7*n^3 - 6*n^2.at n=15A382251
• a(n) = pos(M(n)), where M(n) is the n X n circulant matrix with (row 1) = (F(0), F(1), ..., F(n-1)), where F = A000045 (Fibonacci numbers), and pos(M(n)) is the positive part of the determinant of M(n); see A380661.at n=5A384313