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A317049 Numbers k such that both k and k + 3 are consecutive deficient numbers.

%I A317049 #11 May 28 2019 15:49:38
%S A317049 5774,5983,7423,11023,21734,21943,26143,27403,39374,43063,49663,56923,
%T A317049 58694,61423,69614,70783,76543,77174,79694,81079,81674,82003,84523,
%U A317049 84643,89774,91663,98174,103454,104894,106783,109394,111823,116654,116863,120014,121903
%N A317049 Numbers k such that both k and k + 3 are consecutive deficient numbers.
%H A317049 Muniru A Asiru, <a href="/A317049/b317049.txt">Table of n, a(n) for n = 1..10000</a>
%p A317049 with(numtheory):  A:=select(k->sigma(k)<2*k,[$1..130000]):
%p A317049 a:=seq(A[i],i in select(k->A[k+1]-A[k]=3,[$1..nops(A)-1]));
%t A317049 SequencePosition[Table[If[DivisorSigma[1,n]<2n,1,0],{n,122000}],{1,0,0,1}][[All,1]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, May 28 2019 *)
%o A317049 (GAP) A:=Filtered([1..130000],k->Sigma(k)<2*k);;
%o A317049 a:=List(Filtered([1..Length(A)-1],i->A[i+1]-A[i]=3),j->A[j]);
%Y A317049 Subsequence of A005100.
%Y A317049 Numbers j such that both k and k + j are consecutive deficient numbers: A317047 (j=1), A317048 (j=2), this sequence (j=3).
%K A317049 nonn
%O A317049 1,1
%A A317049 _Muniru A Asiru_, Aug 04 2018