83525

Appears in sequences

• a(n) = n^4+4 = (n^2-2*n+2)*(n^2+2*n+2) = ((n-1)^2+1)*((n+1)^2+1).at n=17A057781
• Numbers k such that 7*10^k + 3*R_k - 2 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=26A103055
• a(n) = a(n-1)^4 + a(n-2)^2, with a(0) = a(1) = 1.at n=4A114950
• Numbers n such that phi(phi(n)) + sigma(sigma(n)) is a 4th power.at n=34A172464
• Beach-Williams Pell numbers of type k^2 + 4.at n=19A212083