cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

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

Original entry on oeis.org

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, 36, 38, 39, 40, 41, 44, 45, 47, 48, 49, 50, 52, 53, 56, 57, 58, 59, 62, 63, 65, 66, 69, 70, 71, 72, 74, 75, 79, 80, 82, 83, 86, 87, 88, 89, 91, 92, 93, 94, 96, 97, 98
Offset: 1

Views

Author

Muniru A Asiru, Aug 04 2018

Keywords

Crossrefs

A317047 is the main sequence for this entry.
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).

Programs

  • GAP
    A:=Filtered([1..150],k->Sigma(k)<2*k);;  a:=Filtered([1..Length(A)-1],i->A[i+1]=A[i]+1);
  • Maple
    with(numtheory): A:=select(k->sigma(k)<2*k,[$1..150]):
      a:=select(j->A[j+1]=A[j]+1,[$1..nops(A)-1]);
  • Mathematica
    Position[Differences[Select[Range[130], DivisorSigma[1, #] < 2*# &]], 1] // Flatten (* Amiram Eldar, Mar 15 2024 *)

Formula

Sequence is { k | A005100(k+1) = A005101(k) + 1 }.
Sequence is { k | A125238(k) = 1 }.

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

Original entry on oeis.org

5, 10, 15, 16, 19, 22, 23, 28, 31, 32, 37, 42, 43, 46, 51, 54, 55, 60, 61, 64, 67, 68, 73, 76, 77, 78, 81, 84, 85, 90, 95, 100, 105, 106, 109, 114, 119, 122, 123, 128, 133, 134, 137, 142, 147, 150, 151, 152, 155, 158, 159, 164, 167, 168, 169, 172, 177, 182
Offset: 1

Views

Author

Muniru A Asiru, Aug 04 2018

Keywords

Crossrefs

A317048 is the main sequence for this entry.
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).

Programs

  • GAP
    A:=Filtered([1..300],k->Sigma(k)<2*k);;  a:=Filtered([1..Length(A)-1],i->A[i+1]=A[i]+2);
  • Maple
    with(numtheory): A:=select(k->sigma(k)<2*k,[$1..300]):
     a:=select(j->A[j+1]=A[j]+2,[$1..nops(A)-1]);
  • Mathematica
    Position[Differences[Select[Range[250], DivisorSigma[1, #] < 2*# &]], 2] // Flatten (* Amiram Eldar, Mar 15 2024 *)

Formula

Sequence is { k | A005100(k+1) = A005101(k) + 2 }.
Sequence is { k | A125238(k) = 2 }.

A317046 Numbers k such that A(k+1) = A(k) + 3, where A() = A005100() are the deficient numbers.

Original entry on oeis.org

4340, 4494, 5572, 8278, 16351, 16506, 19666, 20614, 29619, 32386, 37349, 42805, 44134, 46183, 52345, 53222, 57553, 58033, 59930, 60966, 61412, 61657, 63553, 63643, 67509, 68925, 73829, 77801, 78888, 80309, 82269, 84099, 87737, 87892, 90270, 91697, 91966
Offset: 1

Views

Author

Muniru A Asiru, Aug 04 2018

Keywords

Crossrefs

A317049 is the main sequence for this entry.
Numbers k such that A(k+1) = A(k) + j, where A() = A005100() are the deficient numbers: A317044 (j=1), A317045 (j=2), this sequence (j=3).

Programs

  • GAP
    A:=Filtered([1..130000],k->Sigma(k)<2*k);;  a:=Filtered([1..Length(A)-1],i->A[i+1]=A[i]+3);
  • Maple
    with(numtheory): A:=select(k->sigma(n)<2*k,[$1..130000]):
    a:=select(j->A[j+1]=A[j]+3,[$1..nops(A)-1]);
  • Mathematica
    Position[Differences[Select[Range[125000], DivisorSigma[1, #] < 2*# &]], 3] // Flatten (* Amiram Eldar, Mar 15 2024 *)

Formula

Sequence is { k | A005100(k+1) = A005101(k) + 3 }.
Sequence is { k | A125238(k) = 3 }.
Showing 1-3 of 3 results.