28126

Appears in sequences

• Numbers k such that phi(k)*sigma(k) is a cube.at n=17A114077
• a(2*n+2) = 8*a(2*n+1), a(2*n+1) = 8*a(2*n) - 7^n*A000108(n), a(0)=1.at n=5A156362
• a(n) = 9*5^n+1.at n=5A199313
• Numbers k such that (266*10^k - 11) / 3 is prime.at n=23A277066
• a(n) = the smallest k such that Fibonacci(k) begins and ends with n, where Fibonacci(k) > n, or -1 if there are none.at n=42A374026
• Numbers whose sum of prime divisors equals the sum of square divisors.at n=20A390397