cp's OEIS Frontend

A303741 Numbers k such that A(k+1) = A(k) + 2, where A() = A005101() are the abundant numbers.

%I A303741 #29 Mar 01 2025 03:19:53
%S A303741 2,7,10,14,16,19,22,23,26,31,36,39,44,45,48,51,52,59,62,65,70,71,74,
%T A303741 79,81,82,83,86,87,90,93,96,99,104,107,110,111,114,118,120,125,128,
%U A303741 131,133,135,138,141,146,149,150,155,156,158,164,169,170,175,178,179
%N A303741 Numbers k such that A(k+1) = A(k) + 2, where A() = A005101() are the abundant numbers.
%H A303741 Amiram Eldar, <a href="/A303741/b303741.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..5000 from Muniru A Asiru)
%F A303741 Sequence is { k | A005101(k+1) = A005101(k) + 2 }.
%F A303741 a(n) = A091194(A231086(n)). - _Amiram Eldar_, Mar 01 2025
%p A303741 with(numtheory): A:=select(n->sigma(n)>2*n,[$1..1000]):  a:=select(j->A[j+1]=A[j]+2,[$1..nops(A)-1]);
%t A303741 Position[Differences[Select[Range[750], DivisorSigma[1, #] > 2*# &]], 2] // Flatten (* _Amiram Eldar_, Mar 15 2024 *)
%o A303741 (GAP) A:=Filtered([1..1000],n->Sigma(n)>2*n);;  a:=Filtered([1..Length(A)-1],i->A[i+1]=A[i]+2);
%o A303741 (PARI) list(lim) = {my(k = 1, k2, m = 0); for(k2 = 2, lim, if(sigma(k2, -1) > 2, if(k2 == k1 + 2, print1(m, ", ")); m++; k1 = k2));} \\ _Amiram Eldar_, Mar 01 2025
%Y A303741 A231086 is the main entry for this sequence.
%Y A303741 Cf. A005101, A091194, A096399, A169822.
%K A303741 nonn
%O A303741 1,1
%A A303741 _Muniru A Asiru_, Jun 22 2018