393210

Appears in sequences

• Start with a single triangle; at n-th generation add a triangle at each vertex, allowing triangles to overlap; sequence gives number of triangles in n-th generation.at n=32A061776
• a(1) = 1; thereafter a(n) = 6*(2^(n-1) - 1).at n=16A068293
• Base-10 representation of numbers k which, in base 2, satisfy abs(k + reverse(k) - reverse(k + reverse(k))) = abs(k - reverse(k)) + reverse(abs(k - reverse(k))) = k.at n=21A179697
• Number of idempotent n X n 0..7 matrices of rank n-1.at n=5A224332
• Number of idempotent 6X6 0..n matrices of rank 5.at n=6A224337
• Triangular array read by rows: row n shows the coefficients of this polynomial of degree n: p(x,n) = 2^(n-1) ((x+r)^n - (x+s)^n)/(r - s), where r = 2 and s = 1/2.at n=37A327317