A338569 Number of integers less than n with the same number of ordered factorizations as n.

0, 1, 2, 0, 3, 0, 4, 0, 1, 1, 5, 0, 6, 2, 3, 1, 7, 2, 8, 3, 4, 5, 9, 0, 2, 6, 1, 4, 10, 0, 11, 0, 7, 8, 9, 0, 12, 10, 11, 1, 13, 1, 14, 5, 6, 12, 15, 0, 3, 7, 13, 8, 16, 2, 14, 3, 15, 16, 17, 0, 18, 17, 9, 0, 18, 2, 19, 10, 19, 3, 20, 0, 21, 20, 11, 12, 21, 4, 22, 1

Offset: 1

Author

Ilya Gutkovskiy, Nov 02 2020

Keywords

• nonn

Examples

			a(14) = 2 because A074206(14) = 3 and also A074206(6) = A074206(10) = 3.
		

Links

• Eric Weisstein's World of Mathematics, Ordered Factorization

Crossrefs

Cf. A047983, A074206, A338568.

Programs

Mathematica

A074206[1] = 1; A074206[n_] := A074206[n] = A074206 /@ Most[Divisors[n]] // Total; Table[Length[Select[Range[n - 1], A074206[#] == A074206[n] &]], {n, 80}]

Formula

a(n) = |{j < n : A074206(j) = A074206(n)}|.