161880

Appears in sequences

• Values of B (the even leg) of a Pythagorean triangle with A and C both prime and part of a twin prime.at n=8A051858
• Even legs of Pythagorean triangles whose other leg and hypotenuse are both prime.at n=21A067755
• Numbers k such that sigma(k) = phi((prime(k)+prime(k+1))/2).at n=12A068365
• Numbers k such that k-1, k+1, k^2+1 and k^4+1 are all prime numbers.at n=15A070156
• Numbers n such that n = concatenate(a, b) and sigma(a) + sigma(b) = phi(n).at n=15A249065