21364

Appears in sequences

• Start with a single triangle; at n-th generation add a triangle at each vertex, allowing triangles to overlap; sequence gives total population of triangles at n-th generation.at n=20A061777
• Column 0 of triangle A105542, which equals the matrix square of triangle A105540.at n=18A105543
• Number of self-avoiding walks on a honeycomb lattice with a one-dimensional impenetrable boundary.at n=15A118355
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, -1), (-1, -1, 1), (-1, 1, -1), (1, 0, 1), (1, 1, 0)}.at n=8A150177
• a(n) = 109*n^2.at n=14A174339
• Number of -7..7 arrays x(0..n+1) of n+2 elements with zero sum and no two neighbors summing to zero.at n=2A199831
• T(n,k)=Number of -k..k arrays x(0..n+1) of n+2 elements with zero sum and no two neighbors summing to zero.at n=38A199832
• Number of -n..n arrays x(0..4) of 5 elements with zero sum and no two neighbors summing to zero.at n=6A199834
• Number n such that the sum of its proper evil divisors (A001969) equals n.at n=30A230587
• Number of active (ON, black) cells at stage 2^n-1 of the two-dimensional cellular automaton defined by "Rule 478", based on the 5-celled von Neumann neighborhood.at n=7A272452
• a(n) is the number of integers k in range [2^n, (2^(n+1))-1] such that all terms in finite sequence [k, floor(k/2), floor(k/4), floor(k/8), ..., 1] are squarefree.at n=32A293230
• Numbers that are the sum of five fourth powers in three or more ways.at n=34A344243
• Numbers that are the sum of five fourth powers in exactly three ways.at n=32A344244
• Number of Latin squares of order 2n with maximum inner distance with fixed entry 1 in cell (1,1).at n=11A350453
• Number of integer partitions that are the first sums of some integer partition of n > 0.at n=36A390429