|
%I #14 Jun 18 2019 03:29:45
%S 8,16,24,27,36,40,54,81,88,100,104,120,125,135,136,152,168,184,189,
%T 196,225,232,248,250,264,270,272,280,296,297,312,328,343,344,351,375,
%U 376,378,408,424,440,441,456,459,472,484,488,513,520,536,568,584,594,616
%N Numbers k such that A033831(k) = A034444(k) where A034444(k) = number of unitary divisors of k.
%H Amiram Eldar, <a href="/A033859/b033859.txt">Table of n, a(n) for n = 1..10000</a>
%p with(numtheory): for n from 1 to 1200 do it := divisors(n): count := 0: for i from 1 to nops(it) do if it[i]>=3 and 1<=n/it[i] and n/it[i]<=(it[i]-2) then count := count+1 fi:od: if count=2^nops(ifactors(n)[2]) then printf(`%d,`,n) fi; od:
%t j[n_] := DivisorSum[n, 1&, # > 2 && n/# < #-1 &]; Select[Range[1000], j[#] == 2^PrimeNu[#] &] (* _Amiram Eldar_, Jun 11 2019 *)
%Y Cf. A033831, A034444.
%K easy,nonn
%O 1,1
%A _Naohiro Nomoto_
%E More terms from _James A. Sellers_, Jun 20 2000
|
