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.

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A049485 Primes p such that p + 510510 is also prime, where 510510 is the 7th primorial number A002110(7).

Original entry on oeis.org

19, 41, 43, 59, 71, 73, 79, 101, 103, 107, 109, 167, 173, 181, 197, 199, 241, 257, 263, 283, 293, 307, 313, 317, 337, 379, 397, 409, 421, 431, 433, 479, 491, 503, 509, 523, 547, 577, 599, 601, 613, 641, 643, 653, 659, 661, 683, 691, 701, 727, 733, 751, 769
Offset: 1

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Author

Keywords

Comments

p and p+510510 are not necessarily consecutive primes.

Examples

			19 is a term since it is prime and 19 + 510510 = 510529 is also prime.
		

Crossrefs

Programs

A088766 a(n) = (A087681(n)-1)/2.

Original entry on oeis.org

5, 6, 8, 11, 12, 17, 18, 23, 26, 32, 33, 36, 38, 47, 51, 53, 66, 71, 72, 78, 86, 92, 93, 102, 108, 116, 117, 122, 128, 131, 137, 138, 143, 171, 176, 186, 197, 201, 207, 212, 213, 218, 227, 236, 242, 246, 248, 257, 281, 296, 303, 306, 312, 318, 323, 326, 333, 366
Offset: 1

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Author

Ray Chandler, Oct 26 2003

Keywords

Comments

Numbers k such that 2*k + 1 - 6 and 2*k + 1 + 6 are sexy primes. [Jonathan Vos Post, Feb 14 2011]

Examples

			1002 is in the sequence because 2*1002 + 1 - 6 = 1999 is prime, and 2*1002 + 1 + 6 = 2011 is prime.
		

Crossrefs

Programs

  • Magma
    [n-1: n in [3..400] |IsPrime(2*n+5) and IsPrime(2*n-7)]; // Vincenzo Librandi, May 20 2017
  • Mathematica
    Select[Range[3, 1000], PrimeQ[2 # + 5] && PrimeQ[2 # - 7] &] - 1 (* Vincenzo Librandi, May 20 2017 *)

Formula

{k such that 2*k + 1 - 6 is in A023201} = {k such that 2*k + 1 + 6 is in A046117}.

A140555 Primes p such that p + 6 is not a prime.

Original entry on oeis.org

2, 3, 19, 29, 43, 59, 71, 79, 89, 109, 113, 127, 137, 139, 149, 163, 179, 181, 197, 199, 211, 229, 239, 241, 269, 281, 283, 293, 313, 317, 337, 349, 359, 379, 389, 397, 401, 409, 419, 421, 431, 439, 449, 463, 467, 479, 487, 491, 499, 509, 521, 523, 547, 569
Offset: 1

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Author

Juri-Stepan Gerasimov, Jul 03 2008

Keywords

Comments

Note that if Goldbach's Conjecture (2n = p1 + p2 for all n>=2) is false and K is the smallest value of n for which it fails, then for 2(K-3) = p3 + p4, the primes p3 and p4 must be taken from this list. See also A067775. - Keith Backman, Apr 05 2012

Crossrefs

Programs

  • Mathematica
    Select[Prime[Range[200]],!PrimeQ[#+6]&] (* Harvey P. Dale, Dec 21 2016 *)
  • PARI
    forprime(p=2,600,if(!isprime(p+6),print1(p,","))) \\ Klaus Brockhaus, Aug 12 2008

Formula

A000040 SET MINUS A023201. - R. J. Mathar, Aug 09 2008

Extensions

Corrected by R. J. Mathar and Klaus Brockhaus, Aug 12 2008

A154114 Primes p such that p + 9699690 is also prime, where 9699690 is the 8th primorial number A002110(8).

Original entry on oeis.org

23, 37, 41, 43, 59, 73, 79, 83, 109, 113, 127, 137, 151, 163, 197, 199, 223, 227, 229, 233, 239, 251, 263, 269, 283, 313, 337, 349, 373, 383, 389, 409, 421, 449, 457, 463, 479, 523, 557, 599, 617, 647, 691, 727, 739, 743, 751, 757, 761, 773, 797, 811, 821
Offset: 1

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Author

Keywords

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(1000) | IsPrime(p+9699690)]; // Vincenzo Librandi, Sep 02 2016
    
  • Mathematica
    lst={};Do[p=Prime[n];If[PrimeQ[p+9699690],AppendTo[lst,p]],{n,6!}];lst
    Select[Prime[Range[200]],PrimeQ[#+9699690]&]  (* Harvey P. Dale, Apr 26 2011 *)
  • PARI
    is(n)=isprime(n+9699690) && isprime(n) \\ Charles R Greathouse IV, Sep 02 2016

Formula

a(n) >> n log^2 n. - Charles R Greathouse IV, Sep 02 2016

A164574 Numbers k such that k and k+6 are both prime powers.

Original entry on oeis.org

1, 2, 3, 5, 7, 11, 13, 17, 19, 23, 25, 31, 37, 41, 43, 47, 53, 61, 67, 73, 83, 97, 101, 103, 107, 121, 125, 131, 151, 157, 163, 167, 173, 191, 193, 223, 227, 233, 251, 257, 263, 271, 277, 283, 307, 311, 331, 337, 343, 347, 353, 361, 367, 373, 383, 433, 443, 457
Offset: 1

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Author

Daniel Forgues, Aug 16 2009

Keywords

Comments

Numbers n such that n + (0, 6) is a prime power pair.
n + (0, 2m), m >= 1, being an admissible pattern for prime pairs, since (0, 2m) = (0, 0) (mod 2), has high density.
n + (0, 2m-1), m >= 1, being a non-admissible pattern for prime pairs, since (0, 2m-1) = (0, 1) (mod 2), has low density [the only possible pairs are (2^a - 2m-1, 2^a) or (2^a, 2^a + 2m-1), a >= 0.]

Crossrefs

k and (x) are prime powers: A006549 (k+1) A120431 (k+2), A164571 (k+3), A164572 (k+4), A164573 (k+5), this sequence (k+6).

Programs

  • Mathematica
    Join[{1},Select[Range[500],AllTrue[{#,#+6},PrimePowerQ]&]] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Sep 30 2018 *)
  • PARI
    is(n)=if(n<4,return(n>0)); isprimepower(n) && isprimepower(n+6) \\ Charles R Greathouse IV, Apr 24 2015

Extensions

Edited by Daniel Forgues, Aug 17 2009

A230217 List of those primes p with p + 6 and 3*p + 8 also prime.

Original entry on oeis.org

5, 7, 11, 13, 17, 31, 41, 47, 53, 61, 73, 83, 101, 103, 131, 151, 157, 167, 193, 223, 251, 263, 271, 277, 307, 311, 347, 367, 433, 563, 571, 593, 601, 613, 641, 647, 677, 733, 823, 857, 977, 1097, 1117, 1217, 1223, 1231, 1291, 1301, 1361, 1427
Offset: 1

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Author

Zhi-Wei Sun, Oct 11 2013

Keywords

Comments

Clearly, no term is congruent to 4 modulo 5.
This sequence is interesting because of the conjecture in the comments in A230219.

Examples

			a(1) = 5 since neither 2 + 6 nor 3 + 6 is prime, but 5 + 6 = 11 and 3*5 + 8 = 23 are both prime.
		

Crossrefs

Programs

  • Mathematica
    PQ[p_]:=PrimeQ[p+6]&&PrimeQ[3p+8]
    m=0
    Do[If[PQ[Prime[n]],m=m+1;Print[m," ",Prime[n]]],{n,1,225}]
    Select[Prime[Range[300]],AllTrue[{#+6,3#+8},PrimeQ]&] (* Harvey P. Dale, Sep 01 2023 *)

A049483 Primes p such that p + 2310 is also prime, where 2310 is the 5th primorial number A002110(5).

Original entry on oeis.org

23, 29, 31, 37, 41, 47, 61, 67, 71, 73, 79, 83, 89, 101, 107, 113, 127, 131, 137, 149, 157, 163, 167, 193, 211, 229, 233, 239, 241, 269, 281, 283, 307, 311, 337, 347, 349, 353, 367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 439, 443, 457, 467, 479
Offset: 1

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Author

Keywords

Comments

p and p+2310 are not necessarily consecutive primes.

Examples

			23 is a term since it is prime and 23 + 2310 = 2333 is also prime.
		

Crossrefs

Programs

  • Mathematica
    Select[Prime[Range[100]],PrimeQ[#+2310]&] (* Harvey P. Dale, Nov 15 2012 *)
  • PARI
    isok(p) = isprime(p) && isprime(p + 2310); \\ Amiram Eldar, Mar 15 2025

A049484 Primes p such that p + 30030 is also prime, where 30030 is the 6th primorial number A002110(6).

Original entry on oeis.org

17, 29, 41, 59, 61, 67, 73, 79, 83, 89, 103, 107, 109, 131, 139, 151, 157, 167, 173, 181, 193, 211, 223, 229, 239, 241, 263, 277, 283, 293, 311, 317, 337, 359, 373, 397, 401, 419, 439, 461, 463, 467, 479, 487, 499, 509, 523, 547, 563, 601, 607, 613, 619, 631
Offset: 1

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Author

Keywords

Comments

p and p+30030 are not necessarily consecutive primes.

Examples

			17 is a term since it is prime and 17 + 30030 = 30047 is also prime.
		

Crossrefs

Programs

  • Mathematica
    Select[Prime[Range[150]],PrimeQ[#+30030]&] (* Harvey P. Dale, Sep 21 2022 *)
  • PARI
    isok(p) = isprime(p) && isprime(p + 30030); \\ Amiram Eldar, Mar 15 2025

A103523 Concatenations of pairs of primes that differ by 100.

Original entry on oeis.org

3103, 7107, 13113, 31131, 37137, 67167, 73173, 79179, 97197, 127227, 139239, 151251, 157257, 163263, 181281, 193293, 211311, 283383, 331431, 349449, 367467, 379479, 409509, 421521, 457557, 463563, 487587, 499599, 541641, 547647, 577677
Offset: 1

Views

Author

Jonathan Vos Post, Mar 21 2005

Keywords

Comments

Integers in this sequence can never be prime, as, starting from the second one, they are all multiples of 3.

Examples

			9191019 is in this sequence because 919 is prime, 919+100 = 1019 is prime and 9191019 is the concatenation of those two primes differing by 100.
		

Crossrefs

Programs

  • Maple
    f:= proc(n) if isprime(n) and isprime(n+100) then 10^(1+ilog10(n+100))*n+n+100 fi end proc:
    map(f, [3,seq(i,i=7..1000,6)]); # Robert Israel, Dec 07 2015
  • Mathematica
    FromDigits[Join@@IntegerDigits/@{#,#+100}]&/@Select[Prime@Range@200,PrimeQ[#+100]&] (* Giorgos Kalogeropoulos, Jul 04 2021 *)
  • Python
    from sympy import isprime, primerange as prange
    def auptop(lim):
      return [int(str(p)+str(p+100)) for p in prange(2, lim+1) if isprime(p+100)]
    print(auptop(577)) # Michael S. Branicky, Jul 04 2021

Formula

List: concatenate(p, p+100) iff p and p+100 are primes.

A104227 Primes one less than the sum over a sexy prime pair.

Original entry on oeis.org

19, 31, 67, 79, 127, 139, 151, 199, 211, 307, 547, 619, 739, 751, 919, 1087, 1231, 1459, 1471, 1759, 1987, 2131, 2179, 2239, 2251, 2467, 2647, 2851, 2971, 3319, 3331, 3391, 3499, 3511, 3559, 3571, 3727, 3739, 4027, 4567, 4759, 5107, 5347, 5419, 5431, 6367, 6607, 6619, 7027, 7219, 7459
Offset: 1

Views

Author

Giovanni Teofilatto, Apr 02 2005

Keywords

Comments

Primes of the form A023201(i)+A046117(i)-1 or of the form 2*A087695(j)-1.

Examples

			19=7+13-1 is a prime and one less than the sum 7+13 over the second sexy prime pair.
		

Crossrefs

Programs

  • Mathematica
    Select[2#+5&/@Select[Prime[Range[600]],PrimeQ[#+6]&],PrimeQ] (* Harvey P. Dale, Jan 04 2020 *)

Extensions

Corrected definition. Extended beyond a(7). - R. J. Mathar, Nov 26 2008
Previous Showing 31-40 of 118 results. Next