cp's OEIS Frontend

A317044 Numbers k such that A(k+1) = A(k) + 1, where A() = A005100() are the deficient numbers.

%I A317044 #14 Mar 15 2024 05:38:05
%S A317044 1,2,3,4,6,7,8,9,11,12,13,14,17,18,20,21,24,25,26,27,29,30,33,34,35,
%T A317044 36,38,39,40,41,44,45,47,48,49,50,52,53,56,57,58,59,62,63,65,66,69,70,
%U A317044 71,72,74,75,79,80,82,83,86,87,88,89,91,92,93,94,96,97,98
%N A317044 Numbers k such that A(k+1) = A(k) + 1, where A() = A005100() are the deficient numbers.
%H A317044 Amiram Eldar, <a href="/A317044/b317044.txt">Table of n, a(n) for n = 1..10000</a>
%F A317044 Sequence is { k | A005100(k+1) = A005101(k) + 1 }.
%F A317044 Sequence is { k | A125238(k) = 1 }.
%p A317044 with(numtheory): A:=select(k->sigma(k)<2*k,[$1..150]):
%p A317044   a:=select(j->A[j+1]=A[j]+1,[$1..nops(A)-1]);
%t A317044 Position[Differences[Select[Range[130], DivisorSigma[1, #] < 2*# &]], 1] // Flatten (* _Amiram Eldar_, Mar 15 2024 *)
%o A317044 (GAP) A:=Filtered([1..150],k->Sigma(k)<2*k);;  a:=Filtered([1..Length(A)-1],i->A[i+1]=A[i]+1);
%Y A317044 A317047 is the main sequence for this entry.
%Y A317044 Numbers k such that A(k+1) = A(k) + j, where A() = A005100() are the deficient numbers: this sequence (j=1), A317045 (j=2), A317046 (j=3).
%Y A317044 Cf. A005100, A125238.
%K A317044 nonn
%O A317044 1,2
%A A317044 _Muniru A Asiru_, Aug 04 2018