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

1,1

Links

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

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 *)

Prog

(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]);

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).

Sequence in context: A053862 A235393 A246421 * A329525 A331202 A096399

Adjacent sequences: A317046 A317047 A317048 * A317050 A317051 A317052

Keyword

nonn

Author

Muniru A Asiru, Aug 04 2018

Status

approved