19962

Appears in sequences

• Coordination sequence for Cr3Si, Si position.at n=36A009927
• Dirichlet convolution of 3^(n-1) with sigma(n).at n=9A034753
• In base 2: n sets a new record for the number of 'Reverse and Add' steps needed to reach a palindrome starting with n.at n=13A066144
• Interprimes which are of the form s*prime, s=18.at n=34A075293
• a(n) is the smallest number m such that the sum of the digits of n+m is n.at n=36A130692
• a(n) = A131668(n) - (2*n+1).at n=18A131766
• This is to A139025 as A139025 to A014688, see A139025 for details.at n=34A139026
• Averages of twin primes of the form : i^2+j^2, as sum of two squares.at n=35A143793
• At stage 1, start with a unit equilateral triangle. At each successive stage add 3*(n-1) new triangles around outside with vertex-to-vertex contacts. Sequence gives number of triangles at n-th stage.at n=36A269064
• a(0) = 1; a(n) = a(n-1) + Sum_{k=0..n-1} binomial(k+4,5) * a(k) * a(n-1-k).at n=5A386455