220113

Appears in sequences

• a(0) = 1 by convention; for n>0, a(n) is the number of points in the n-th figure shown in A255011 (meaning the figure with 4n points on the perimeter).at n=14A331449
• Odd numbers k such that phi(k) = phi(k+2), where phi is the Euler totient function (A000010).at n=17A333741