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 1-5 of 5 results.

A134933 a(n)=A134930(n)/2.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 14, 15, 16, 20, 21, 22, 29, 30, 31, 35, 36, 37, 50, 51, 52, 53, 54, 55, 68, 69, 70, 74, 75, 76, 89, 90, 91, 95, 96, 97, 98, 99, 100, 113, 114, 115, 119, 120, 121, 134, 135, 136, 140, 141, 142, 155, 156, 157
Offset: 1

Views

Author

Omar E. Pol, Nov 22 2007

Keywords

Comments

Nearest-neighbors of twin primes, divided by 2.

Examples

			a(11)=14 because A134930(11)=28 and we can write 28/2=14.

Crossrefs

Cf. A134930.

Formula

a(n)=A134932(n-1), n>1. [From R. J. Mathar, Oct 27 2008]

A147819 Nearest-neighbors of odd primes.

Original entry on oeis.org

2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 28, 30, 32, 36, 38, 40, 42, 44, 46, 48, 52, 54, 58, 60, 62, 66, 68, 70, 72, 74, 78, 80, 82, 84, 88, 90, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 126, 128, 130, 132, 136, 138, 140, 148, 150, 152, 156, 158, 162
Offset: 1

Views

Author

Omar E. Pol, Nov 14 2008

Keywords

Links

Crossrefs

Cf. A000040, A045718, A065091, A134924, A134930.

Programs

  • Mathematica
    #+{-1,1}&/@Prime[Range[2,60]]//Flatten//Union (* Harvey P. Dale, Jun 13 2017 *)

A134924 Nearest-neighbors of isolated primes.

Original entry on oeis.org

1, 3, 22, 24, 36, 38, 46, 48, 52, 54, 66, 68, 78, 80, 82, 84, 88, 90, 96, 98, 112, 114, 126, 128, 130, 132, 156, 158, 162, 164, 166, 168, 172, 174, 210, 212, 222, 224, 232, 234, 250, 252, 256, 258, 262, 264, 276, 278, 292, 294, 306, 308
Offset: 1

Views

Author

Omar E. Pol, Nov 27 2007

Keywords

Links

Crossrefs

Cf. A007510, A045718, A134926, A134930.

Programs

  • Mathematica
    ip=Select[Prime[Range[65]],NoneTrue[{#-2,#+2},PrimeQ]&];Union[Flatten[Table[n+{1, -1}, {n, ip}]]] (* James C. McMahon, Apr 12 2025 *)

A210940 The prime numbers and their nonprime nearest-neighbors.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 13, 14, 16, 17, 18, 19, 20, 22, 23, 24, 28, 29, 30, 31, 32, 36, 37, 38, 40, 41, 42, 43, 44, 46, 47, 48, 52, 53, 54, 58, 59, 60, 61, 62, 66, 67, 68, 70, 71, 72, 73, 74, 78, 79, 80, 82, 83, 84, 88, 89, 90, 96, 97, 98, 100
Offset: 1

Views

Author

Omar E. Pol, Apr 17 2012

Keywords

Comments

The prime numbers and their nearest-neighbors without repetitions.

Crossrefs

Union of A210939 and A000040. Complement of A079364.
Cf. A018252, A045718, A134928, A134930.

Programs

  • Mathematica
    {#-1,#,#+1}&/@Prime[Range[30]]//Flatten//Union (* Harvey P. Dale, Jul 06 2019 *)

Extensions

Corrected (74 added) by Harvey P. Dale, Jul 06 2019

A210939 Nonprime nearest-neighbors of the primes.

Original entry on oeis.org

1, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 28, 30, 32, 36, 38, 40, 42, 44, 46, 48, 52, 54, 58, 60, 62, 66, 68, 70, 72, 74, 78, 80, 82, 84, 88, 90, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 126, 128, 130, 132, 136, 138, 140, 148, 150, 152, 156
Offset: 1

Views

Author

Omar E. Pol, Apr 17 2012

Keywords

Comments

Essentially the same as A147819. R. J. Mathar, Jun 25 2012

Crossrefs

Nonprimes in A045718.
Cf. A000040, A018252, A134928, A134930, A210940.

Programs

  • Mathematica
    Select[Range[156], ! PrimeQ[#] && (PrimeQ[# - 1] || PrimeQ[# + 1]) &] (* T. D. Noe, Apr 18 2012 *)
Join[{1},Flatten[#+{-1,1}&/@Prime[Range[3,40]]]//Union] (* Harvey P. Dale, Oct 22 2022 *)
Showing 1-5 of 5 results.

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

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