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 1-8 of 8 results.

A078946 Primes p such that p, p+2, p+6, p+12 and p+14 are consecutive primes.

Original entry on oeis.org

17, 227, 1277, 1607, 3527, 3917, 4637, 4787, 27737, 38447, 39227, 44267, 71327, 97367, 99707, 113147, 122027, 122387, 124337, 165707, 183497, 187127, 191447, 197957, 198827, 275447, 290657, 312197, 317957, 347057, 349397, 416387, 418337, 421697, 427067, 443867
Offset: 1

Views

Author

Labos Elemer, Dec 19 2002

Keywords

Examples

			227 is in the sequence since 227, 229 = 227 + 2, 233 = 227 + 6, 239 = 227 + 12 and 241 = 227 + 14 are consecutive primes.
		

Crossrefs

Subsequence of A128468.
Subsequence of A078847. - R. J. Mathar, Feb 10 2013

Programs

  • Magma
    [p: p in PrimesInInterval(7,1000000) | forall{i: i in [2,6,12,14] | IsPrime(p+i)}]; // Vincenzo Librandi, Apr 19 2015
  • Mathematica
    Rest@ Select[Prime@ Range@ 36000, AllTrue[{2, 6, 12, 14} + #, PrimeQ] &] (* Michael De Vlieger, Apr 18 2015, Version 10 *)
    Select[Partition[Prime[Range[36000]],5,1],Differences[#]=={2,4,6,2}&][[All,1]] (* Harvey P. Dale, Jun 14 2022 *)
  • PARI
    isok(p) = isprime(p) && (nextprime(p+1)==p+2) && (nextprime(p+3)== p+6) && (nextprime(p+7)==p+12) && (nextprime(p+13)==p+14); \\ Michel Marcus, Dec 10 2013
    
  • PARI
    list(lim) = {my(p1 = 2, p2 = 3, p3 = 5, p4 = 7); forprime(p5 = 11, lim, if(p2 - p1 == 2 && p3 - p2 == 4 && p4 - p3 == 6 && p5 - p4 == 2, print1(p1, ", ")); p1 = p2; p2 = p3; p3 = p4; p4 = p5);} \\ Amiram Eldar, Feb 21 2025
    

Formula

a(n) == 17 (mod 30). - Amiram Eldar, Feb 21 2025

Extensions

Edited by Dean Hickerson, Dec 20 2002

A253624 Initial members of prime sextuples (p, p+2, p+12, p+14, p+24, p+26).

Original entry on oeis.org

5, 17, 1277, 4217, 21587, 91127, 103967, 113147, 122027, 236867, 342047, 422087, 524957, 560477, 626597, 754967, 797567, 909317, 997097, 1322147, 1493717, 1698857, 1748027, 1762907, 2144477, 2158577, 2228507, 2398157, 2580647, 2615957
Offset: 1

Views

Author

Karl V. Keller, Jr., Jan 06 2015

Keywords

Comments

This sequence is primes p for which there exist three twin prime pairs (p, p+2), (p+12, p+14) and (p+24, p+26).
Excluding 5, this is a subsequence of each of the following: A128468 (a(n)=30n+17). A039949 (Primes of the form 30n-13), A181605 (twin primes ending in 7).
Note that not in all cases (p, p+2, p+12, p+14, p+24, p+26) are consecutive primes; the first p's for which (p, p+2, p+12, p+14, p+24, p+26) are consecutive primes are 4217, 21587, 91127, 103967, 236867, 342047, 422087, 560477, 797567, 909317, 1322147, 1493717, 1748027, 1762907, 2144477, 2158577, 2228507, 2615957 (not in OEIS). - Zak Seidov, May 16 2017

Examples

			For p = 17, the numbers 17, 19, 29, 31, 41, 43 are primes.
		

Crossrefs

Cf. A077800 (twin primes), A128468, A039949, A181605.

Programs

  • Maple
    select(t -> andmap(isprime, [t,t+2,t+12,t+14,t+24,t+26]),
    [5, seq(30*k+17,k=0..10^5)]); # Robert Israel, Jan 07 2015
  • Mathematica
    Select[Prime@ Range[2*10^5], Times @@ Boole@ PrimeQ[# + {2, 12, 14, 24, 26}] == 1 &] (* Michael De Vlieger, May 16 2017 *)
    Select[Prime[Range[200000]],AllTrue[#+{2,12,14,24,26},PrimeQ]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jun 15 2021 *)
  • Python
    from sympy import isprime
    for n in range(1,10000001,2):
      if isprime(n) and isprime(n+2) and isprime(n+12) and isprime(n+14) and isprime(n+24) and isprime(n+26): print(n,end=', ')
    
  • Python
    from sympy import isprime, primerange
    def aupto(limit):
      alst = []
      for p in primerange(2, limit+1):
        if all(map(isprime, [p+2, p+12, p+14, p+24, p+26])): alst.append(p)
      return alst
    print(aupto(3*10**6)) # Michael S. Branicky, May 17 2021

A267984 Numbers congruent to {17, 23} mod 30.

Original entry on oeis.org

17, 23, 47, 53, 77, 83, 107, 113, 137, 143, 167, 173, 197, 203, 227, 233, 257, 263, 287, 293, 317, 323, 347, 353, 377, 383, 407, 413, 437, 443, 467, 473, 497, 503, 527, 533, 557, 563, 587, 593, 617, 623, 647, 653, 677, 683, 707, 713, 737, 743, 767, 773
Offset: 1

Views

Author

Arkadiusz Wesolowski, Jan 23 2016

Keywords

Comments

Union of A128468 and A128473.
For all k >= 1 the numbers 2^k + a(n) and a(n)*2^k + 1 do not form a pair of primes, where n is any positive integer.

Crossrefs

Programs

  • Magma
    [n: n in [0..773] | n mod 30 in {17, 23}];
    
  • Mathematica
    LinearRecurrence[{1, 1, -1}, {17, 23, 47}, 52]
  • PARI
    Vec(x*(17 + 6*x + 7*x^2)/((1 + x)*(1 - x)^2) + O(x^53))

Formula

a(n) = a(n-1) + a(n-2) - a(n-3), n >= 4.
G.f.: x*(17 + 6*x + 7*x^2)/((1 + x)*(1 - x)^2).
a(n) = a(n-2) + 30.
a(n) = 10*(3*n - 2) - a(n-1).
From Colin Barker, Jan 24 2016: (Start)
a(n) = (30*n - 9*(-1)^n - 5)/2 for n>0.
a(n) = 15*n - 7 for n>0 and even.
a(n) = 15*n + 2 for n odd.
(End)
E.g.f.: 7 + ((30*x - 5)*exp(x) - 9*exp(-x))/2. - David Lovler, Sep 10 2022

A375645 Products of prime 7-tuples (p, p+2, p+8, p+12, p+14, p+18, p+20) where p = A022010(n).

Original entry on oeis.org

183698727318433150098859517, 43573095131179423946916455382173477, 151752127452301913425377267345374694407, 37933916719513692044984369353553394500687, 336012768546310957228958479424678156040797, 2608471791567290523882206574758483434858457, 523352977400310485591027030692542102863968347677
Offset: 1

Views

Author

Michael De Vlieger, Aug 23 2024

Keywords

Comments

Primes p in A022010 belong to 179 (mod 210), therefore a(n) is congruent to the product of residues {179, 181, 187, 191, 193, 197, 199} (mod 210), so a(n) is congruent to 17 (mod 210). Gaps between prime factors are {2, 6, 4, 2, 4, 2}.

Crossrefs

Programs

  • Mathematica
    Map[Times @@ NextPrime[#, Range[0, 6]] &, Select[Prime@ Range[2^20], AllTrue[# + {2, 8, 12, 14, 18, 20}, PrimeQ] &]]

A245568 Initial members of prime quadruples (n, n+2, n+24, n+26).

Original entry on oeis.org

5, 17, 617, 857, 1277, 1427, 1697, 2087, 2687, 3557, 4217, 5417, 5477, 7307, 8837, 9437, 10067, 13877, 17657, 18287, 20747, 21587, 23537, 25577, 27917, 28547, 30467, 32117, 32297, 35507, 37337, 37547, 40127, 41177, 41387, 41957
Offset: 1

Views

Author

Karl V. Keller, Jr., Jan 09 2015

Keywords

Comments

This sequence is prime n, where there exist two twin prime pairs of (n, n+2, n+24, n+26).
Excluding 5, this is a subsequence of each of the following: A128468 (a(n) = 30*n + 17), A039949 (Primes of the form 30n-13), A181605 (twin primes ending in 7).
A253624 is a subsequence of this sequence.

Examples

			For n = 17, the numbers 17, 19, 41, 43 are primes.
		

Crossrefs

Cf. A077800 (twin primes), A128468, A039949, A181605, A253624.

Programs

  • Mathematica
    a245568[n_] := Select[Prime@ Range@ n, And[PrimeQ[# + 2], PrimeQ[# + 24], PrimeQ[# + 26]] &]; a245568[5000] (* Michael De Vlieger, Jan 11 2015 *)
  • Python
    from sympy import isprime
    for n in range(1,10000001,2):
      if isprime(n) and isprime(n+2) and isprime(n+24) and isprime(n+26): print(n,end=', ')

A248474 Numbers congruent to 13 or 17 mod 30.

Original entry on oeis.org

13, 17, 43, 47, 73, 77, 103, 107, 133, 137, 163, 167, 193, 197, 223, 227, 253, 257, 283, 287, 313, 317, 343, 347, 373, 377, 403, 407, 433, 437, 463, 467, 493, 497, 523, 527, 553, 557, 583, 587, 613, 617, 643, 647, 673, 677, 703, 707, 733, 737, 763, 767, 793, 797
Offset: 1

Views

Author

Karl V. Keller, Jr., Oct 06 2014

Keywords

Comments

The combination of A082369(30*n+13) and A128468(30*n+17) is the base sequence for A140533(Primes congruent to 13 or 17 mod 30).

Crossrefs

Cf. A082369 (30*n+13), A128468 (30*n+17).
Cf. A039949 (Primes of the form 30n-13), A132233 (Primes congruent to 13 mod 30), A140533 (Primes congruent to 13 or 17 mod 30).

Programs

  • Mathematica
    Flatten[Table[{15n - 2, 15n + 2}, {n, 1, 41, 2}]] (* Alonso del Arte, Oct 06 2014 *)
  • PARI
    Vec(x*(13*x^2+4*x+13)/((x-1)^2*(x+1)) + O(x^100)) \\ Colin Barker, Oct 07 2014
  • Python
    for n in range(1,101):
      print (n*30-17),
      print (n*30-13),
    

Formula

From Colin Barker, Oct 07 2014: (Start)
a(n) = (-15-11*(-1)^n+30*n)/2.
a(n) = a(n-1)+a(n-2)-a(n-3).
G.f.: x*(13*x^2+4*x+13) / ((x-1)^2*(x+1)). (End)
E.g.f.: 13 + ((30*x - 15)*exp(x) - 11*exp(-x))/2. - David Lovler, Sep 10 2022
Sum_{n>=1} (-1)^(n+1)/a(n) = (sqrt(2*(5+sqrt(5)))+sqrt(3)-sqrt(15))*Pi / (30*(sqrt(6*(5+sqrt(5)))+sqrt(5)-1)). - Amiram Eldar, Jul 30 2024

A248523 Initial members of prime quadruples (n, n+2, n+144, n+146).

Original entry on oeis.org

5, 137, 1787, 1997, 2237, 2657, 3527, 4127, 4337, 4787, 8087, 12107, 13757, 14447, 17987, 19697, 21377, 23057, 23687, 31247, 32297, 34157, 34367, 35447, 37547, 38567, 39227, 43397, 48677, 51197, 51827, 53087, 58907, 65027, 65837
Offset: 1

Views

Author

Karl V. Keller, Jr., Jan 11 2015

Keywords

Comments

This sequence is prime n, where there exist two twin prime pairs of (n,n+2), (n+144,n+146).
Excluding 5, this is a subsequence of each of the following: A128468 (a(n)=30*n+17), A039949 (Primes of the form 30n-13), A181605 (twin primes ending in 7).

Examples

			For n=137, the numbers 137, 139, 281, 283, are primes.
		

Crossrefs

Cf. A077800 (twin primes), A128468, A039949, A181605.

Programs

  • Python
    from sympy import isprime
    for n in range(1,10000001,2):
        if isprime(n) and isprime(n+2) and isprime(n+144) and isprime(n+146): print(n,end=', ')

A248661 Initial members of prime quadruples (n, n+2, n+54, n+56).

Original entry on oeis.org

5, 17, 137, 227, 827, 1427, 1667, 1877, 2027, 2087, 2657, 3527, 3767, 4217, 4967, 10037, 11117, 11777, 12107, 13877, 17987, 19697, 20717, 21557, 22037, 23687, 24977, 27527, 27737, 34157, 37307, 41177, 42017, 42407, 47657, 48677
Offset: 1

Views

Author

Karl V. Keller, Jr., Jan 11 2015

Keywords

Comments

This sequence is prime n, where there exist two twin prime pairs of (n,n+2), (n+54,n+56).
Excluding 5, this is a subsequence of each of the following: A128468 (a(n)=30*n+17), A039949 (primes, 30n-13), A181605 (twin primes, end 7), and A092340 (prime n, where n^2+2*n divides (fibonacci(n^2)+fibonacci(2*n))).

Examples

			For n=17, the numbers 17, 19, 71, 73, are primes.
		

Crossrefs

Cf. A077800 (twin primes), A128468, A039949, A181605, A092340.

Programs

  • Python
    from sympy import isprime
    for n in range(1,10000001,2):
      if isprime(n) and isprime(n+2) and isprime(n+54) and isprime(n+56): print(n,end=', ')
Showing 1-8 of 8 results.