3145722

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=38A061776
• a(1) = 1; thereafter a(n) = 6*(2^(n-1) - 1).at n=19A068293
• The smallest superharmonic number with index n.at n=17A152573
• 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=35A179697
• Even integers k such that phi(sum of even divisors of k) = sum of odd divisors of k.at n=27A281707