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 1-10 of 13 results. Next

A031936 Lower prime of a difference of 18 between consecutive primes.

Original entry on oeis.org

523, 1069, 1259, 1381, 1759, 1913, 2161, 2503, 2861, 3803, 3889, 4159, 4373, 4423, 4463, 4603, 4703, 4733, 5059, 5209, 5483, 6011, 6229, 6451, 6529, 6581, 6619, 7159, 7351, 7393, 7433, 7459, 7621, 7883, 8191, 8761, 9109, 9293, 9749
Offset: 1

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Author

Keywords

Comments

Subsequence of A153418: a(1)=523=A153418(46), a(2)=1069=A153418(80), etc. - Zak Seidov, Sep 13 2015
No terms are congruent to 7 mod 10. - Michel Marcus, Sep 14 2015

Crossrefs

Cf. A153418.

Programs

  • Magma
    [p: p in PrimesUpTo(10000) | NextPrime(p)-p eq 18]; // Bruno Berselli, Apr 09 2013
    
  • Mathematica
    Transpose[Select[Partition[Prime[Range[1300]], 2, 1], Last[#] - First[#] == 18 &]][[1]] (* Bruno Berselli, Apr 09 2013 *)
  • PARI
    isok(p) = isprime(p) && (nextprime(p+1) == p+18); \\ Michel Marcus, Sep 14 2015

Formula

a(n) = prime(A320707(n)). - R. J. Mathar, Apr 30 2024

A156104 Primes p such that p+36 is also prime.

Original entry on oeis.org

5, 7, 11, 17, 23, 31, 37, 43, 47, 53, 61, 67, 71, 73, 101, 103, 113, 127, 131, 137, 157, 163, 191, 193, 197, 227, 233, 241, 257, 271, 277, 281, 311, 313, 317, 331, 337, 347, 353, 373, 383, 397, 421, 431, 443, 463, 467, 487, 521, 541, 557, 563, 571, 577, 607
Offset: 1

Views

Author

Vincenzo Librandi, Feb 08 2009

Keywords

Crossrefs

Cf. A156112.
Cf. sequences of the type p+n are primes: A001359 (n=2), A023200 (n=4), A023201 (n=6), A023202 (n=8), A023203 (n=10), A046133 (n=12), A153417 (n=14), A049488 (n=16), A153418 (n=18), A153419 (n=20), A242476 (n=22), A033560 (n=24), A252089 (n=26), A252090 (n=28), A049481 (n=30), A049489 (n=32), A252091 (n=34), this sequence (n=36); A062284 (n=50), A049490 (n=64), A156105 (n=72), A156107 (n=144).

Programs

  • Magma
    [p: p in PrimesUpTo(1000) | IsPrime(p + 36)]; // Vincenzo Librandi, Oct 31 2012
  • Mathematica
    Select[Prime[Range[1000]], PrimeQ[(#+ 36)]&] (* Vincenzo Librandi, Oct 31 2012 *)

A153419 Primes p such that p+20 is also prime.

Original entry on oeis.org

3, 11, 17, 23, 41, 47, 53, 59, 83, 89, 107, 131, 137, 173, 179, 191, 251, 257, 263, 293, 311, 317, 347, 353, 359, 389, 401, 419, 443, 467, 479, 503, 521, 557, 587, 593, 599, 641, 653, 719, 809, 839, 857, 863, 887, 947, 971, 977, 1013, 1019, 1031, 1049, 1097
Offset: 1

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Author

Keywords

Examples

			3 is in the sequence because 3+20=23 is prime; 11 is in the sequence because 11+20=31 is prime.
		

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(1100) | IsPrime(p + 20)]; // Vincenzo Librandi, Apr 14 2013
  • Maple
    for a from 1 to 140 do if isprime(a) and isprime(a+20) then print(a)
      end if;  end do; # Matt C. Anderson, Jun 20 2022
  • Mathematica
    Select[Prime[Range[200]], PrimeQ[(# + 20)]&] (* Vincenzo Librandi, Apr 14 2013 *)

Extensions

Definition improved from Bruno Berselli, Oct 31 2012

A252089 Primes p such that p + 26 is prime.

Original entry on oeis.org

3, 5, 11, 17, 41, 47, 53, 71, 83, 101, 113, 131, 137, 167, 173, 197, 251, 257, 281, 311, 347, 353, 383, 431, 461, 521, 587, 593, 617, 647, 683, 701, 743, 761, 797, 827, 857, 881, 911, 941, 971, 983, 1013, 1061, 1091, 1097, 1103, 1187, 1223, 1277, 1301, 1373
Offset: 1

Views

Author

Vincenzo Librandi, Dec 14 2014

Keywords

Examples

			17 is in this sequence because 17+26 = 43 is prime.
431 is in this sequence because 431+26 = 457 is prime.
		

Crossrefs

Cf. sequences of the type p+n are primes: A001359 (n=2), A023200 (n=4), A023201 (n=6), A023202 (n=8), A023203 (n=10), A046133 (n=12), A153417 (n=14), A049488 (n=16), A153418 (n=18), A153419 (n=20), A242476 (n=22), A033560 (n=24), this sequence (n=26), A252090 (n=28), A049481 (n=30), A049489 (n=32), A252091 (n=34), A156104 (n=36); A062284 (n=50), A049490 (n=64), A156105 (n=72), A156107 (n=144).

Programs

  • Magma
    [NthPrime(n): n in [1..250] | IsPrime(NthPrime(n)+26)];
  • Mathematica
    Select[Prime[Range[200]], PrimeQ[# + 26] &]

A156328 List of prime pairs of the form (p, p+18).

Original entry on oeis.org

5, 23, 11, 29, 13, 31, 19, 37, 23, 41, 29, 47, 41, 59, 43, 61, 53, 71, 61, 79, 71, 89, 79, 97, 83, 101, 89, 107, 109, 127, 113, 131, 131, 149, 139, 157, 149, 167, 163, 181, 173, 191, 179, 197, 181, 199, 193, 211, 211, 229, 223, 241, 233, 251, 239, 257, 251, 269, 263
Offset: 1

Views

Author

Vincenzo Librandi, Feb 08 2009

Keywords

Comments

The two primes p and p+18 are not necessarily adjacent.

Crossrefs

Cf. A153418.

Programs

  • Mathematica
    Flatten[Select[{#, # + 18} &/@Prime[Range[1000]], PrimeQ[Last[#]]&]] (* Vincenzo Librandi, Nov 01 2012 *)

A161723 Middle members p of prime triples (p-18,p,p+18).

Original entry on oeis.org

23, 29, 41, 61, 71, 79, 89, 131, 149, 181, 211, 251, 331, 349, 401, 439, 449, 461, 659, 691, 701, 709, 751, 769, 839, 929, 1031, 1051, 1069, 1231, 1301, 1471, 1549, 1601, 1619, 1741, 1759, 1889, 1931, 2011, 2081, 2161, 2221, 2269, 2399, 2441, 2459, 2521
Offset: 1

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Author

Keywords

Comments

The three primes p-18, p and p+18 are not necessarily consecutive.

Examples

			23 is the middle in the triple of three primes (23-18=5, 23, 23+18=41) with arithmetic progression 18.
		

Crossrefs

Programs

  • Mathematica
    q=6*3; lst={}; Do[p=Prime[n]; If[PrimeQ[p-q] && PrimeQ[p+q], AppendTo[lst,p]], {n, 5000}]; lst
    Select[Prime[Range[7,400]],AllTrue[#+{18,-18},PrimeQ]&] (* Harvey P. Dale, Apr 21 2024 *)

Formula

{p: p in A153418 and p-18 in A153418} - R. J. Mathar, Sep 22 2009

Extensions

Rephrased the definition - R. J. Mathar, Sep 22 2009

A231608 Table whose n-th row consists of primes p such that p + 2n is also prime, read by antidiagonals.

Original entry on oeis.org

3, 3, 5, 5, 7, 11, 3, 7, 13, 17, 3, 5, 11, 19, 29, 5, 7, 11, 13, 37, 41, 3, 7, 13, 23, 17, 43, 59, 3, 5, 11, 19, 29, 23, 67, 71, 5, 7, 17, 17, 31, 53, 31, 79, 101, 3, 11, 13, 23, 19, 37, 59, 37, 97, 107, 7, 11, 13, 31, 29, 29, 43, 71, 41, 103, 137
Offset: 1

Views

Author

T. D. Noe, Nov 26 2013

Keywords

Examples

			The following sequences are read by antidiagonals
{3, 5, 11, 17, 29, 41, 59, 71, 101, 107,...}
{3, 7, 13, 19, 37, 43, 67, 79, 97, 103,...}
{5, 7, 11, 13, 17, 23, 31, 37, 41, 47,...}
{3, 5, 11, 23, 29, 53, 59, 71, 89, 101,...}
{3, 7, 13, 19, 31, 37, 43, 61, 73, 79,...}
{5, 7, 11, 17, 19, 29, 31, 41, 47, 59,...}
{3, 5, 17, 23, 29, 47, 53, 59, 83, 89,...}
{3, 7, 13, 31, 37, 43, 67, 73, 97, 151,...}
{5, 11, 13, 19, 23, 29, 41, 43, 53, 61,...}
{3, 11, 17, 23, 41, 47, 53, 59, 83, 89,...}
...
		

Crossrefs

Cf. A020483 (numbers in first column).
Cf. A086505 (numbers on the diagonal).

Programs

  • Maple
    A231608 := proc(n,k)
        local j,p ;
        j := 0 ;
        p := 2;
        while j < k do
            if isprime(p+2*n ) then
                j := j+1 ;
            end if;
            if j = k then
                return p;
            end if;
            p := nextprime(p) ;
        end do:
    end proc:
    for n from 1 to 10 do
        for k from 1 to 10 do
            printf("%3d ",A231608(n,k)) ;
        end do;
        printf("\n") ;
    end do: # R. J. Mathar, Nov 19 2014
  • Mathematica
    nn = 10; t = Table[Select[Range[100*nn], PrimeQ[#] && PrimeQ[# + 2*n] &, nn], {n, nn}]; Table[t[[n-j+1, j]], {n, nn}, {j, n}]

A156109 Primes p such that p+18 and p+36 are both prime.

Original entry on oeis.org

5, 11, 23, 43, 53, 61, 71, 113, 131, 163, 193, 233, 313, 331, 383, 421, 431, 443, 641, 673, 683, 691, 733, 751, 821, 911, 1013, 1033, 1051, 1213, 1283, 1453, 1531, 1583, 1601, 1723, 1741, 1871, 1913, 1993, 2063, 2143, 2203, 2251, 2381, 2423, 2441, 2503
Offset: 1

Views

Author

Vincenzo Librandi, Feb 08 2009

Keywords

Comments

A153418 INTERSECT A156104. [Bruno Berselli, Nov 01 2012]

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(3000)|IsPrime(p + 18) and IsPrime (p + 36)]; // Vincenzo Librandi, Oct 31 2012
  • Maple
    a := proc (n) if isprime(ithprime(n)+18) = true and isprime(ithprime(n)+36) = true then ithprime(n) else end if end proc: seq(a(n), n = 1 .. 400); # Emeric Deutsch, Mar 02 2009
  • Mathematica
    Select[Prime[Range[3000]], And @@ PrimeQ[{# + 18, # + 36}]&] (* Vincenzo Librandi, Oct 31 2012 *)

Extensions

More terms from Emeric Deutsch, Mar 02 2009

A156110 Primes p such that p+18 and p+72 are both prime.

Original entry on oeis.org

11, 29, 41, 79, 109, 139, 179, 211, 239, 349, 431, 449, 491, 569, 601, 701, 739, 751, 809, 811, 839, 911, 919, 991, 1021, 1031, 1051, 1091, 1231, 1289, 1301, 1381, 1409, 1471, 1481, 1549, 1759, 1861, 1931, 2011, 2069, 2081, 2221, 2269, 2339, 2459, 2521
Offset: 1

Views

Author

Vincenzo Librandi, Feb 08 2009

Keywords

Comments

A153418 INTERSECT A156105. [Bruno Berselli, Nov 01 2012]

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(3000)|IsPrime(p + 18) and IsPrime (p + 72)]; // Vincenzo Librandi, Oct 31 2012
  • Mathematica
    Select[Prime[Range[3000]], And @@ PrimeQ[{# + 18, # + 72}]&] (* Vincenzo Librandi, Oct 31 2012 *)

A156111 Primes p such that p+18 and p+144 are both prime.

Original entry on oeis.org

5, 13, 19, 23, 29, 53, 79, 83, 89, 113, 139, 149, 163, 173, 193, 223, 239, 313, 379, 443, 449, 503, 599, 613, 643, 683, 709, 733, 739, 743, 809, 839, 919, 953, 1069, 1153, 1163, 1279, 1283, 1289, 1303, 1409, 1453, 1493, 1549, 1553, 1579, 1609, 1723, 1993, 1999
Offset: 1

Views

Author

Vincenzo Librandi, Feb 08 2009

Keywords

Comments

A153418 INTERSECT A156107. [Bruno Berselli, Nov 01 2012]

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(2000)|IsPrime(p + 18) and IsPrime (p + 144)]; // Vincenzo Librandi, Oct 30 2012
  • Mathematica
    Select[Prime[Range[2000]], And @@ PrimeQ[{# + 18, # + 144}]&] (* Vincenzo Librandi, Oct 30 2012 *)

Extensions

13 inserted and extended by R. J. Mathar, Feb 19 2009
Showing 1-10 of 13 results. Next