cp's OEIS Frontend

A317045 Numbers k such that A(k+1) = A(k) + 2, where A() = A005100() are the deficient numbers.

%I A317045 #11 Mar 15 2024 05:38:28
%S A317045 5,10,15,16,19,22,23,28,31,32,37,42,43,46,51,54,55,60,61,64,67,68,73,
%T A317045 76,77,78,81,84,85,90,95,100,105,106,109,114,119,122,123,128,133,134,
%U A317045 137,142,147,150,151,152,155,158,159,164,167,168,169,172,177,182
%N A317045 Numbers k such that A(k+1) = A(k) + 2, where A() = A005100() are the deficient numbers.
%H A317045 Amiram Eldar, <a href="/A317045/b317045.txt">Table of n, a(n) for n = 1..10000</a>
%F A317045 Sequence is { k | A005100(k+1) = A005101(k) + 2 }.
%F A317045 Sequence is { k | A125238(k) = 2 }.
%p A317045 with(numtheory): A:=select(k->sigma(k)<2*k,[$1..300]):
%p A317045  a:=select(j->A[j+1]=A[j]+2,[$1..nops(A)-1]);
%t A317045 Position[Differences[Select[Range[250], DivisorSigma[1, #] < 2*# &]], 2] // Flatten (* _Amiram Eldar_, Mar 15 2024 *)
%o A317045 (GAP) A:=Filtered([1..300],k->Sigma(k)<2*k);;  a:=Filtered([1..Length(A)-1],i->A[i+1]=A[i]+2);
%Y A317045 A317048 is the main sequence for this entry.
%Y A317045 Numbers k such that A(k+1) = A(k) + j, where A() = A005100() are the deficient numbers: A317044 (j=1), this sequence (j=2), A317046 (k=3).
%Y A317045 Cf. A005100, A125238.
%K A317045 nonn
%O A317045 1,1
%A A317045 _Muniru A Asiru_, Aug 04 2018