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A228300 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, 15, 110, 170, 273, 638, 935, 1394, 2093, 2438, 2465, 4823, 5453, 7973, 11978, 16354, 17963, 34918, 43337, 46943, 62491, 64583, 68266, 71603, 72046, 74347, 75361, 85877, 134458, 148291, 155933, 186235, 188071, 201994, 209933, 280891, 307021, 367081 (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 17963 are 11, 23 and 71 while d(17963) = 8. We have that 17963 - 8 = 17955 and 17955 / (11 - 8) =  5985, 17955 / (23 - 8) = 1197 and 17955 / (71 - 8) = 285.

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, A228301, A228302.

Sequence in context: A229276 A319035 A117309 * A299996 A315289 A108936

Adjacent sequences:  A228297 A228298 A228299 * A228301 A228302 A228303

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 June 3 05:29 EDT 2020. Contains 334798 sequences. (Running on oeis4.)