77140

Appears in sequences

• For a rational number p/q let f(p/q) = p*q divided by (the sum of digits of p and of q) minus 1; a(n) is obtained by iterating f, starting at n/1, until an integer is reached, or if no integer is ever reached then a(n) = 0.at n=57A059514
• Numbers k such that 1+k, 1+k^2, 1+k^4 and 1+k^16 are all prime.at n=5A188698
• a(n) = n*(n+1)*(7*n-6)/2.at n=28A256718