51216

Appears in sequences

• a(n) = Sum_{k=m..n} T(k,n-k), where m = floor((n+1)/2); a(n) is the n-th diagonal-sum of left justified array T given by A027948.at n=27A027959
• Expansion of 1/(1-2*x-2*x^2+2*x^3).at n=12A077937
• Expansion of 1/(1+2*x-2*x^2-2*x^3).at n=12A077981
• Expansion of 1/(1 - x - x^3 + x^5).at n=52A123552
• Number of isosceles triangles that can be formed from the n^2 points of n X n grid of points (or geoboard).at n=13A186434
• Number of length 4+1 0..n arrays with the sum of the cubes of adjacent differences multiplied by some arrangement of +-1 equal to zero.at n=18A250231
• Draw a regular n-gon and the enclosing circle, then for each pair of vertices X, Y, draw a circle with diameter XY; the union of these figures is the graph H_n; sequence gives number of edges in H_n.at n=21A370979
• Expansion of (1/x) * Series_Reversion( x / ( (1+x)^2 * (1+2*x)^2 ) ).at n=5A371406