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A338569 Number of integers less than n with the same number of ordered factorizations as n. 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..80.

Eric Weisstein's World of Mathematics, Ordered Factorization

FORMULA

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

EXAMPLE

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

MATHEMATICA

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

CROSSREFS

Cf. A047983, A074206, A338568.

Sequence in context: A352740 A108416 A215395 * A343757 A108760 A343554

Adjacent sequences: A338566 A338567 A338568 * A338570 A338571 A338572

KEYWORD

nonn

AUTHOR

Ilya Gutkovskiy, Nov 02 2020

STATUS

approved

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Last modified January 29 18:12 EST 2023. Contains 359926 sequences. (Running on oeis4.)