327660

Appears in sequences

• a(n+3) = 3*a(n+2) - 2*a(n+1) + 1 with a(0)=1, a(1)=5.at n=16A094002
• Expansion of (1-3*x+6*x^2-3*x^3)/((1-x)^2*(1-2*x)).at n=17A188589
• Number of pairs of intersecting diagonals in the interior and exterior of a regular n-gon.at n=40A211380
• Number of intersections of diagonals in the interior and exterior of a regular n-gon.at n=40A211383
• Draw a square and follow these steps: Take a square and place at its edges isosceles right triangles with the edge as hypotenuse. Draw a square at every new edge of the triangles. Repeat for all the new squares of the same size. New figures are only placed on empty space. The structure is symmetric about the first square. The sequence gives the numbers of squares of equal size in successive rings around the center.at n=28A265207
• a(n) is the period of the oscillating pattern formed by a 1 X n line of cells in the Life-like cellular automaton B2c3-cekq4ikt5i8/S2-in3-acky4aijry5eiky6i, or 0 if the pattern vanishes.at n=56A298819