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 1-4 of 4 results.

A140445 List of prime pairs of form p, p + 10.

Original entry on oeis.org

3, 13, 7, 17, 13, 23, 19, 29, 31, 41, 37, 47, 43, 53, 61, 71, 73, 83, 79, 89, 97, 107, 103, 113, 127, 137, 139, 149, 157, 167, 163, 173, 181, 191, 223, 233, 229, 239, 241, 251, 271, 281, 283, 293, 307, 317, 337, 347, 349, 359, 373, 383, 379, 389, 409, 419, 421
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Jun 26 2008

Keywords

Crossrefs

Cf. A023203 (1st bisection), A092146 (2nd bisection).
Cf. prime pairs of the form (p, p+k): A077800 (k=2), A094343 (k=4), A156274 (k=6), A156320 (k=8), this sequence (k=10), A156323 (k=12), A140446 (k=14), A272815 (k=16), A156328 (k=18), A272816 (k=20), A140447 (k=22).

Programs

  • Maple
    i: 1: for k from 1 to 1200 do if isprim (k) and isprim (k+10) then a [ i ] : = k : a [ i + 1]: = k + 10 : i = i + 2 fi od : seq (a [ n ], n=1..i-1);
  • Mathematica
    Flatten[{#,#+10}&/@Select[Prime[Range[100]],PrimeQ[#+10]&]]  (* Harvey P. Dale, Apr 11 2011 *)

Extensions

Corrected by D. S. McNeil, Dec 10 2009

A272815 Prime pairs of the form (p, p+16).

Original entry on oeis.org

3, 19, 7, 23, 13, 29, 31, 47, 37, 53, 43, 59, 67, 83, 73, 89, 97, 113, 151, 167, 157, 173, 163, 179, 181, 197, 211, 227, 223, 239, 241, 257, 277, 293, 331, 347, 337, 353, 367, 383, 373, 389, 433, 449, 463, 479, 487, 503, 541, 557, 547, 563, 571
Offset: 1

Views

Author

Vincenzo Librandi, May 07 2016

Keywords

Comments

p and p+16 are not necessarily consecutive primes: (1831, 1847) is the first pair of consecutive primes that belongs to the sequence.

Examples

			The prime pairs are (3, 19), (7, 23), (13, 29) etc.
		

Crossrefs

Cf. prime pairs of the form (p, p+k): A077800 (k=2), A094343 (k=4), A156274 (k=6), A156320 (k=8), A140445 (k=10), A156323 (k=12), A140446 (k=14), this sequence (k=16), A156328 (k=18), A272816 (k=20), A140447 (k=22).

Programs

  • Magma
    &cat [[p,p+16]: p in PrimesUpTo(1000) | IsPrime(p+16)];
  • Mathematica
    Flatten[{#, # + 16}&/@Select[Prime[Range[200]], PrimeQ[# + 16] &]]

Formula

a(2n+1) = A049488(n+1).

A272816 Prime pairs of the form (p, p+20).

Original entry on oeis.org

3, 23, 11, 31, 17, 37, 23, 43, 41, 61, 47, 67, 53, 73, 59, 79, 83, 103, 89, 109, 107, 127, 131, 151, 137, 157, 173, 193, 179, 199, 191, 211, 251, 271, 257, 277, 263, 283, 293, 313, 311, 331, 317, 337, 347, 367, 353, 373, 359, 379, 389, 409, 401, 421
Offset: 1

Views

Author

Vincenzo Librandi, May 07 2016

Keywords

Comments

p and p+20 are not necessarily consecutive primes: (887, 907) is the first pair of consecutive primes that belongs to the sequence.

Examples

			The prime pairs are (3, 23), (11, 31), (17, 37) etc.
		

Crossrefs

Cf. similar sequences listed in A272815.
Prime pairs of the form (p, p+k): A077800 (k=2), A094343 (k=4), A156274 (k=6), A156320 (k=8), A140445 (k=10), A156323 (k=12), A140446 (k=14), A272815 (k=16), A156328 (k=18), this sequence (k=20), A140447 (k=22).

Programs

  • Magma
    &cat [[p, p+20]: p in PrimesUpTo(1000) | IsPrime(p+20)];
    
  • Mathematica
    Flatten[{#, # + 20}&/@Select[Prime[Range[200]], PrimeQ[# + 20] &]]
  • Python
    from gmpy2 import is_prime
    for n in range(1000):
       if(is_prime(n) and is_prime(n+20)):
          print('{}, {}'.format(n,n+20),end=', ')
    # Soumil Mandal, May 14 2016

Formula

a(2n+1) = A153419(n+1).

Extensions

Edited by Bruno Berselli, May 12 2016

A329262 Prime pairs of the form (30k - 7, 30k + 7).

Original entry on oeis.org

23, 37, 53, 67, 83, 97, 113, 127, 263, 277, 293, 307, 353, 367, 383, 397, 443, 457, 563, 577, 593, 607, 743, 757, 773, 787, 863, 877, 953, 967, 983, 997, 1103, 1117, 1223, 1237, 1283, 1297, 1433, 1447, 1553, 1567, 1583, 1597, 1613, 1627
Offset: 1

Views

Author

Harry E. Neel, Nov 09 2019

Keywords

Comments

The terms of this sequence are created by pairing the terms of the primes when the terms 30k - 7 and 30k + 7 are both prime. As has been pointed out, it is only a guess as to whether, or not, that (like the twin primes, etc.) there is or is not an infinite number of these pairings.

Examples

			As 4 * 30 - 7 = 113 and 4 * 30 + 7 = 127 are prime, both 113 and 127 are in the sequence. - _David A. Corneth_, Nov 10 2019
		

Crossrefs

Odd- (resp. even-) indexed terms are a subsequence of A132235 (resp. A132231).

Programs

  • Magma
    &cat[[30*k-7] cat [30*k+7]:k in [1..60]|IsPrime(30*k-7) and IsPrime(30*k+7)]; // Marius A. Burtea, Nov 17 2019
  • Mathematica
    Select[Prime[Range[1000]], MemberQ[{7, 23}, Mod[#, 30]] &] (* Jinyuan Wang, Nov 16 2019 *)
    Flatten[Select[Table[30n + {-7, 7}, {n, 90}], PrimeQ[#[[1]]] && PrimeQ[#[[2]]] &]] (* Alonso del Arte, Dec 07 2019 *)
  • PARI
    first(n) = n+=(n%2); my(res=List(),todo=n); for(i=1,oo, if(isprime(30*i-7) && isprime(30*i+7), listput(res,30*i-7); listput(res,30*i+7); todo-=2; if(todo<=0, return(res)))) \\ David A. Corneth, Nov 10 2019
    
Showing 1-4 of 4 results.