18009

Appears in sequences

• Number of primes between n^4 and (n+1)^4.at n=40A061235
• a(1) = 1, a(n) = a(n-1) + phi(a(n-1)).at n=19A074693
• Positions of zeros in A165597.at n=30A165598
• Numbers k such that phi(phi(k)) = sigma(rad(k)).at n=26A173748
• Numbers x such that the sum of all their cyclic permutations is equal to that of all cyclic permutations of sigma(x) and all cyclic permutations of Euler totient function phi(x).at n=13A247317
• Number of length 4+4 0..n arrays with every five consecutive terms having four times some element equal to the sum of the remaining four.at n=7A249660