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

5774, 5983, 7423, 11023, 21734, 21943, 26143, 27403, 39374, 43063, 49663, 56923, 58694, 61423, 69614, 70783, 76543, 77174, 79694, 81079, 81674, 82003, 84523, 84643, 89774, 91663, 98174, 103454, 104894, 106783, 109394, 111823, 116654, 116863, 120014, 121903

Offset: 1

Author

Muniru A Asiru, Aug 04 2018

Keywords

• nonn

Links

• Muniru A Asiru, Table of n, a(n) for n = 1..10000

Crossrefs

Subsequence of A005100.

Numbers j such that both k and k + j are consecutive deficient numbers: A317047 (j=1), A317048 (j=2), this sequence (j=3).

Programs

GAP

A:=Filtered([1..130000],k->Sigma(k)<2*k);;
a:=List(Filtered([1..Length(A)-1],i->A[i+1]-A[i]=3),j->A[j]);

Maple

with(numtheory):  A:=select(k->sigma(k)<2*k,[$1..130000]):
a:=seq(A[i],i in select(k->A[k+1]-A[k]=3,[$1..nops(A)-1]));

Mathematica

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 *)