451535

Appears in sequences

• Nonsquarefree "year numbers" (numbers n such that phi(n) = 2*phi(sigma(n)): A137815).at n=18A137816
• Number of (n+2) X (1+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00000101 00010101 or 01010101.at n=14A260008