18578

Appears in sequences

• sec(sinh(x)*exp(x))=1+1/2!*x^2+6/3!*x^3+33/4!*x^4+220/5!*x^5...at n=7A012522
• Numbers k such that 8^k == -1 (mod k-1).at n=13A055691
• Expansion of 1/(1-x+x^2-2*x^3).at n=35A077951
• Number of ways to place zero or more nonadjacent 0,0 1,0 1,1 2,0 2,1 2,2 polyhexes in any orientation on a planar nXnXn triangular grid.at n=9A155249
• Number of unlabeled 5-trees on n nodes.at n=13A201702
• Number of (w,x,y,z) with all terms in {0,...,n} and w=max{w,x,y,z}-min{w,x,y,z}; i.e., the range of (w,x,y,z) is its first term.at n=21A212744
• Number of (n+2)X(4+2) 0..1 arrays with each 3X3 subblock having clockwise perimeter pattern 00000001 00001001 or 00100101.at n=7A260976
• Molien series for invariants of finite Coxeter group D_10 (bisected).at n=38A266773
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 211", based on the 5-celled von Neumann neighborhood.at n=30A270899
• Number of set partitions of [n] such that for each block b the smallest integer interval containing b has at most four elements.at n=12A276720
• Start from the singleton set S = {n}, and unless 1 is already a member of S, generate on each iteration a new set where each odd number k is replaced by 3k+1, and each even number k is replaced by 3k+1 and k/2. a(n) is the size of the set after the first iteration which has produced 1 as a member.at n=38A290100
• Irregular table read by rows, T(n, k) is the rank of the k-th Seidel permutation of {1,...,n}, permutations sorted in lexicographical order.at n=32A347600
• The fixed points of A355702.at n=46A356017
• Number of integer partitions of n such that the least part plus the greatest part is odd.at n=39A390092