cp's OEIS Frontend

A379031 Odd modified exponential abundant numbers: odd numbers k such that A241405(k) > 2*k.

%I A379031 #10 Dec 16 2024 02:16:30
%S A379031 15015,19635,21945,23205,25935,26565,31395,33495,33915,35805,39585,
%T A379031 41055,42315,42735,45885,47355,49665,50505,51765,54285,55965,58695,
%U A379031 61215,64155,68145,70455,72345,77385,80535,82005,83265,84315,91245,95865,102795,112035,116655
%N A379031 Odd modified exponential abundant numbers: odd numbers k such that A241405(k) > 2*k.
%C A379031 First differs from its subsequences A112643 and A249263 at n = 51: a(51) = 195195 is not a term of these two sequences.
%C A379031 First differs from its subsequence A129485 at n = 363: a(363) = 2537535 is not a term of A129485.
%C A379031 First differs from A339938 at n = 28: A339938(28) = 75075 is not a term of this sequence.
%C A379031 First differs from A360526 at n = 46: A360526(46) = 165165 is not a term of this sequence.
%H A379031 Amiram Eldar, <a href="/A379031/b379031.txt">Table of n, a(n) for n = 1..10000</a>
%t A379031 f[p_, e_] := DivisorSum[e + 1, p^(# - 1) &]; mesigma[1] = 1; mesigma[n_] := Times @@ f @@@ FactorInteger[n]; meAbQ[n_] := mesigma[n] > 2*n; Select[Range[1, 10^5, 2], meAbQ]
%o A379031 (PARI) is(k) = if(!(k%2), 0, my(f=factor(k)); prod(i=1, #f~, sumdiv(f[i, 2]+1, d, f[i, 1]^(d-1))) > 2*k);
%Y A379031 Intersection of A005408 and A379029.
%Y A379031 Subsequence of A005231.
%Y A379031 Subsequences: A112643, A129485, A249263.
%Y A379031 Cf. A241405.
%Y A379031 Similar sequences: A094889, A127666, A129485, A293186, A321147, A339938, A348275, A360526.
%K A379031 nonn,easy
%O A379031 1,1
%A A379031 _Amiram Eldar_, Dec 14 2024