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A228301 Composite squarefree numbers n such that p-d(n) divides n+d(n), where p are the prime factors of n and d(n) the number of divisors of n. 5
6, 10, 14, 15, 35, 70, 154, 190, 322, 385, 442, 595, 682, 2737, 3619, 14986, 15314, 19019, 24817, 26767, 33626, 78387, 85034, 130169, 155363, 166934, 189727, 214107, 225029, 238901, 243217, 285934, 381547, 395219, 415679, 417989, 455609, 466193, 544918 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Subsequence of A120944.

LINKS

Donovan Johnson, Table of n, a(n) for n = 1..500

EXAMPLE

Prime factors of 19019 are 7, 11, 13 and 19 while d(19019) = 16. We have that 19019 + 16 = 19035 and 19035 / (7 - 16) =  -2115, 19035 / (11 - 16) =  -3807, 19035 / (13 - 16) = -6345 and 19035 / (19 - 16) = 6345.

MAPLE

with (numtheory); P:=proc(q) local a, b, c, i, ok, p, n;

for n from 2 to q do  if not isprime(n) then a:=ifactors(n)[2]; ok:=1;

for i from 1 to nops(a) do if a[i][2]>1 or a[i][1]=tau(n) then ok:=0; break;

else if not type((n+tau(n))/(a[i][1]-tau(n)), integer) then ok:=0; break; fi; fi; od; if ok=1 then print(n); fi; fi; od; end: P(10^6);

CROSSREFS

Cf. A000005, A228299, A228300, A228302.

Sequence in context: A242920 A183072 A225704 * A193416 A315160 A075777

Adjacent sequences:  A228298 A228299 A228300 * A228302 A228303 A228304

KEYWORD

nonn

AUTHOR

Paolo P. Lava, Aug 20 2013

EXTENSIONS

First term deleted by Paolo P. Lava, Sep 23 2013

STATUS

approved

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Last modified July 11 08:50 EDT 2020. Contains 335626 sequences. (Running on oeis4.)