A367577 a(n) is the first k such that A367566(k) = n, or -1 if no such k exists.

252, 1, 2, -1, 24, 5, 48, -1, -1, -1, 450, -1, 12, 15, 4, -1, 1512, -1, 18, -1, -1, 45, 8118, -1, -1, -1, -1, -1, 840, -1, 30, -1, 10, -1, 6, -1, 1368, 189, -1, -1, 1680, -1, 42, -1, -1, 231, 2208, -1, -1, -1, 152, -1, 6942, -1, -1, -1, -1, -1, 27318, -1, 60

Offset: 1

Author

Jon E. Schoenfield, Nov 24 2023

Keywords

• sign

Comments

a(n) = -1 iff n is nonsquarefree or is divisible by some term in A367576.

Examples

			a(1) = 252 because 1 first appears as a term in A367566 at A367566(252).
a(4) = -1 because 4 = 2^2 is nonsquarefree so it never appears in A367566.
a(10) = -1 because 10 is a term in A367576.
a(42) = -1 because 21 divides 42, and 21 is a term in A367576.
		

Crossrefs

Cf. A367566, A367576.