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.

A137624 Complement of A120632.

Original entry on oeis.org

1, 3, 5, 6, 7, 9, 10, 12, 13, 14, 15, 16, 17, 19, 20, 21, 23, 24, 25, 26, 27, 28, 30, 31, 32, 34, 35, 36, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 52, 53, 55, 56, 57, 58, 59, 60, 61, 62, 63, 65, 66, 67, 68, 69, 70, 71, 73, 74, 75, 77, 78, 79, 80, 81, 82, 83, 85, 86
Offset: 1

Views

Author

Reinhard Zumkeller, Jan 30 2008

Keywords

Comments

A137621(a(n)) = A018252(n).

A137621 Divisors of nonprimes not occurring earlier.

Original entry on oeis.org

1, 2, 4, 3, 6, 8, 9, 5, 10, 12, 7, 14, 15, 16, 18, 20, 21, 11, 22, 24, 25, 13, 26, 27, 28, 30, 32, 33, 17, 34, 35, 36, 19, 38, 39, 40, 42, 44, 45, 23, 46, 48, 49, 50, 51, 52, 54, 55, 56, 57, 29, 58, 60, 31, 62, 63, 64, 65, 66, 68, 69, 70, 72, 37, 74, 75, 76, 77, 78, 80, 81, 41
Offset: 1

Views

Author

Reinhard Zumkeller, Jan 30 2008

Keywords

Comments

Permutation with inverse A137622; A137623(n) = a(a(n)).
a(A120632(n))=A000040(n); a(A120632(n)+1)=A100484(n); a(A137624(n))=A018252(n).

Examples

			1;2,4;3,6;8;9;5,10;12;7,14;15;16;18;20;21;11,22;24; .. .

Links

Programs

  • Mathematica
    s={};Do[If[!PrimeQ[n],s=Join[s,Complement[Divisors[n],s]]],{n,81}];s (* James C. McMahon, Jun 01 2025 *)

A120633 Number of composite numbers bounded inclusively between p(n+1) and 2*p(n) where p(x) is prime(x).

Original entry on oeis.org

1, 1, 3, 2, 7, 7, 12, 12, 13, 22, 19, 25, 31, 31, 33, 37, 45, 44, 51, 56, 55, 61, 63, 66, 75, 80, 81, 87, 88, 82, 101, 103, 111, 105, 121, 120, 124, 132, 134, 140, 148, 142, 158, 158, 164, 156, 165, 182, 188, 188, 189, 199, 193, 205, 210
Offset: 1

Views

Author

Lekraj Beedassy, Jun 21 2006

Keywords

Programs

Formula

a(n) = A062234(n) - A070046(n) + 1 = A120632(n) - A040976(n+1).

Extensions

Definition clarified by Harvey P. Dale, Oct 01 2019
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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