A375605 Number of composite knots with n crossings.

0, 0, 0, 0, 0, 0, 2, 1, 5

Offset: 0

Author

Jens Ahlström, Aug 20 2024

Keywords

• nonn
• hard
• more
• bref

Comments

A knot is composite if and only if it can be written as the knot sum of two nontrivial knots.

Examples

			For n = 6 there are totally 5 knots out of which 3 are prime, so a(6) = 5 - 3 = 2.
		

Crossrefs

Cf. A086825, A002863.

Formula

a(n) = A086825(n) - A002863(n), for all n > 0.