253009

Appears in sequences

• a(n) = prime^2 and digits of prime appear in a(n).at n=10A030081
• Composite numbers k such that the sum of the divisors of k^2 is a prime.at n=38A065405
• Numbers k such that sigma_4(k)/sigma_2(k) is prime.at n=25A066109
• Smallest number > n beginning with n and with the prime signature of n.at n=23A086547
• Numbers k such that sigma(k) - phi(k) is a brilliant number (A078972).at n=34A115917
• Squares in A111153.at n=25A175255
• Number of n X 4 0..1 arrays avoiding 0 0 1 and 0 1 1 horizontally and 0 0 1 and 1 1 0 vertically.at n=20A207399
• Perfect squares which can be written neither as a^2+b^2, nor as a^2+2*b^2, nor as a^2+3*b^2, nor as a^2+7*b^2, with a > 0 and b > 0.at n=6A216408