cp's OEIS Frontend

A129485 Odd unitary abundant numbers.

%I A129485 #14 Feb 16 2025 08:33:05
%S A129485 15015,19635,21945,23205,25935,26565,31395,33495,33915,35805,39585,
%T A129485 41055,42315,42735,45885,47355,49665,50505,51765,54285,55965,58695,
%U A129485 61215,64155,68145,70455,72345,77385,80535,82005,83265,84315,91245,95865,102795,112035
%N A129485 Odd unitary abundant numbers.
%C A129485 This sequence is different from A112643. The two sequences agree for the first 50 terms but differ thereafter. The exceptions, i.e. those odd unitary abundant numbers that are not squarefree ordinary abundant numbers, are in A129486.
%C A129485 22309287 is the smallest term not divisible by 5. 33426748355 is the smallest term not divisible by 3. - _Donovan Johnson_, May 15 2013
%C A129485 The numbers of terms not exceeding 10^k, for k = 5, 6, ..., are 34, 137, 1714, 16918, 181744, 1752337, 17290556, ... . Apparently, the asymptotic density of this sequence exists and equals 0.00017... . - _Amiram Eldar_, Sep 02 2022
%H A129485 Donovan Johnson, <a href="/A129485/b129485.txt">Table of n, a(n) for n = 1..10000</a>
%H A129485 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/UnitaryDivisor.html">Unitary Divisor</a>.
%F A129485 This sequence contains the odd members of A034683. i.e. odd numbers with a positive unitary abundance (A129468).
%e A129485 The third odd unitary abundant number is 21945. Hence a(3) = 21945.
%p A129485 # see A034683 for the code of isA034683()
%p A129485 isA129485 := proc(n)
%p A129485     type(n,'odd') and isA034683(n) ;
%p A129485 end proc:
%p A129485 for n from 1 do
%p A129485     if isA129485(n) then
%p A129485         print(n);
%p A129485     end if;
%p A129485 end do: # _R. J. Mathar_, Nov 10 2014
%t A129485 UnitaryDivisors[n_Integer?Positive]:=Select[Divisors[n],GCD[ #,n/# ]==1&];sstar[n_]:=Plus@@UnitaryDivisors[n]-n;Select[Range[1,10^5,2],sstar[ # ]># &]
%Y A129485 Cf. A034683, A129486, A034460, A034448, A129487, A002827, A129468, A112643.
%K A129485 easy,nonn
%O A129485 1,1
%A A129485 _Ant King_, Apr 17 2007