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A293234 a(n) is the number of proper divisors of n that are square. 3
0, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 2, 2, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 2, 1, 1, 1, 2, 2, 1, 1, 3, 1, 2, 1, 2, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 2, 3, 1, 1, 1, 2, 1, 1, 1, 4, 1, 1, 2, 2, 1, 1, 1, 3, 2, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 1, 1, 1, 3, 1, 2, 2, 3, 1, 1, 1, 2, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,8

COMMENTS

First occurrence of k: 2, 8, 32, 72, 144, 288, 576, 1152, 2304, 4608, 3600, 7200, 36864, 20736, 14400, 28800, 32400, 64800, 57600, 115200, 663552, 18874368, 129600, 259200, 3359232, 810000, 921600, 1843200, 518400, 1036800, 705600, 1411200, etc. - Robert G. Wilson v, Oct 08 2017

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..16384

Index entries for sequences computed from exponents in factorization of n

FORMULA

a(n) = Sum_{d|n, d<n} A010052(d).

a(n) = A046951(n) - A010052(n).

MATHEMATICA

f[n_] := Length@ Select[ Sqrt@ Most@ Divisors@ n, IntegerQ]; Array[f, 105] (* Robert G. Wilson v, Oct 08 2017 *)

PROG

(PARI) A293234(n) = sumdiv(n, d, (d<n)*ispower(d, 2));

CROSSREFS

Cf. A010052, A046951, A293227, A293235.

Sequence in context: A161099 A118663 A205119 * A102097 A318749 A050330

Adjacent sequences:  A293231 A293232 A293233 * A293235 A293236 A293237

KEYWORD

nonn

AUTHOR

Antti Karttunen, Oct 08 2017

STATUS

approved

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Last modified February 21 19:49 EST 2020. Contains 332110 sequences. (Running on oeis4.)