89188

Appears in sequences

• Numbers k such that 40*R_k + 9 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=9A056683
• a(0)=1; a(n) = sigma_2(n) + sigma_3(n).at n=42A092344
• Number of (n+2) X 4 0..1 arrays with every 3 X 3 subblock having three equal elements in a row horizontally, vertically or nw-to-se diagonally exactly three ways, and new values 0..1 introduced in row major order.at n=19A204375