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 112 results. Next

A248166 Prime quadruples: a(n) = A007530(1000n).

Original entry on oeis.org

11721791, 31210841, 54112601, 78984791, 106583831, 136466501, 165939791, 196512551, 230794301, 265201421, 301001081, 335176481, 373855121, 411947141, 449008031, 486394031, 527311061, 568016921, 605541611, 648107891, 688455791, 731157611, 771988571, 814329401, 855214271, 896639321, 939594371, 983009771, 1028559401, 1073336981, 1116991871, 1162958981, 1208506331
Offset: 1

Views

Author

Zak Seidov, Oct 16 2014

Keywords

Comments

All terms are congruent to {11,101,191} mod 210.
First 10 terms coincide with values due to M. F. Hasler (see A007530).

Crossrefs

Cf. A007530.

A088268 Palindromes in A007530.

Original entry on oeis.org

5, 11, 101, 191, 16061, 1748471, 179868971, 11027472011, 13160106131, 15130003151, 15843234851, 16420302461, 16782228761, 16861316861, 17060706071, 17374347371, 18491419481, 18697979681, 19497279491
Offset: 1

Views

Author

Amarnath Murthy, Sep 28 2003

Keywords

Comments

Conjecture: Sequence is finite.

Crossrefs

Cf. A007530.

Programs

  • Mathematica
    Select[Prime[Range[8611*10^5]],AllTrue[#+{2,6,8},PrimeQ] && PalindromeQ[ #]&] (* Requires Mathematica version 10 or later *) (* The program will take a long time to run *) (* Harvey P. Dale, Mar 11 2019 *)

Extensions

More terms from David Wasserman, Jul 28 2005

A358198 a(n) is the first member p of A007530 such that, with q = p+2, r = p+6 and s = p+8, (2*p+q)/5 is a prime and (r+2*s)/5^n is a prime.

Original entry on oeis.org

11, 101, 243701, 6758951, 3257480201, 5493848951, 58634348951, 218007942701, 21840280598951, 213065296223951, 186522444661451, 383378987630201, 7794174397786451, 110420241292317701, 67327687581380201, 91455128987630201, 3987035878499348951, 80659241994222005201, 4289429982503255201
Offset: 1

Views

Author

J. M. Bergot and Robert Israel, Nov 02 2022

Keywords

Examples

			a(3) = 243701 because p = 247301, q = p+2 = 247303, r = p+6 = 243707, s = p+8 = 243709, (2*p+q)/5 = 146221 and (r+2*s)/5^3 = 5849 are primes, and p is the least prime that works.
		

Crossrefs

Programs

  • Maple
    f:= proc(n) local t,p,m;
            m:= 5^n;
            t:= 3;
            do
              t:= nextprime(t);
              if t*m mod 3 <> 1 then next fi;
              p:= (t*m-22)/3;
              if isprime(p) and isprime(p+2) and isprime(p+6) and isprime(p+8) and isprime((3*p+2)/5) then return p fi;
            od;
    end proc;
    map(f, [$1..20]);
  • Mathematica
    a[n_] := a[n] = Module[{t = 3, p, m = 5^n}, While[True, t = NextPrime[t]; If[Mod[t*m, 3] != 1, Continue[]]; p = (t*m - 22)/3; If[AllTrue[{p, p+2, p+6, p+8, (3p+2)/5}, PrimeQ], Return[p]]]];
    Table[Print[n, " ", a[n]]; a[n], {n, 1, 19}] (* Jean-François Alcover, Jan 31 2023, after Maple program *)

A022006 Initial members p of prime 5-tuples (p, p+2, p+6, p+8, p+12).

Original entry on oeis.org

5, 11, 101, 1481, 16061, 19421, 21011, 22271, 43781, 55331, 144161, 165701, 166841, 195731, 201821, 225341, 247601, 268811, 326141, 347981, 361211, 397751, 465161, 518801, 536441, 633461, 633791, 661091, 768191, 795791, 829721, 857951, 876011, 958541
Offset: 1

Views

Author

Keywords

Comments

Subsequence of A007530. - R. J. Mathar, Feb 10 2013
All terms, except for the first one, are congruent to 11 (modulo 30). - Matt C. Anderson, May 22 2015
For n > 1 and p = a(n), (p, p+2, p+6, p+8, p+12) are consecutive primes. - Zak Seidov, Jun 07 2017
A022007 is a similar sequence. - Wolfdieter Lang, Oct 06 2017

Examples

			Admissible 5-tuple guaranteeing sequence example: for prime(3) = 5 the first residue class starting with a nonnegative number and containing none of the members of (0, 2, 6, 8, 12) is 4 (mod 5). - _Wolfdieter Lang_, Oct 06 2017
		

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(2*10^6) | IsPrime(p+2) and IsPrime(p+6) and IsPrime(p+8) and IsPrime(p+12)]; // Vincenzo Librandi, May 23 2015
    
  • Mathematica
    lst={};Do[p=Prime[n];If[PrimeQ[p+2]&&PrimeQ[p+6]&&PrimeQ[p+8]&&PrimeQ[p+12], AppendTo[lst, p]], {n, 9!}];lst (* Vladimir Joseph Stephan Orlovsky, Sep 25 2008 *)
    Transpose[Select[Partition[Prime[Range[64000]],5,1],Differences[#] == {2,4,2,4}&]][[1]] (* Harvey P. Dale, Dec 08 2014 *)
  • PARI
    forprime(p=2,1e7, if(isprime(p+2) && isprime(p+6) && isprime(p+8) && isprime(p+12), print1(p", "))) \\ Charles R Greathouse IV, Jul 19 2011
    
  • Perl
    use ntheory ":all"; say for sieve_prime_cluster(1,1e7, 2,6,8,12); # Dana Jacobsen, Sep 30 2015
    
  • Python
    from sympy import primerange
    def aupto(limit):
      p, q, r, s, alst = 2, 3, 5, 7, []
      for t in primerange(11, limit+13):
        if p+2 == q and p+6 == r and p+8 == s and p+12 == t: alst.append(p)
        p, q, r, s = q, r, s, t
      return alst
    print(aupto(10**6)) # Michael S. Branicky, May 11 2021

Extensions

Missing terms a(51) and a(52) added in b-file by Dana Jacobsen, Sep 30 2015

A007811 Numbers k for which 10k+1, 10k+3, 10k+7 and 10k+9 are primes.

Original entry on oeis.org

1, 10, 19, 82, 148, 187, 208, 325, 346, 565, 943, 1300, 1564, 1573, 1606, 1804, 1891, 1942, 2101, 2227, 2530, 3172, 3484, 4378, 5134, 5533, 6298, 6721, 6949, 7222, 7726, 7969, 8104, 8272, 8881, 9784, 9913, 10111, 10984, 11653, 11929, 12220, 13546, 14416, 15727
Offset: 1

Views

Author

N. J. A. Sloane and J. H. Conway, Mar 15 1996

Keywords

Crossrefs

Programs

  • Haskell
    a007811 n = a007811_list !! (n-1)
    a007811_list = map (pred . head) $ filter (all (== 1) . map a010051') $
       iterate (zipWith (+) [10, 10, 10, 10]) [1, 3, 7, 9]
    -- Reinhard Zumkeller, Jul 18 2014
    
  • Magma
    [n: n in [0..10000] | forall{10*n+r: r in [1,3,7,9] | IsPrime(10*n+r)}]; // Bruno Berselli, Sep 04 2012
    
  • Maple
    for n from 1 to 10000 do m := 10*n: if isprime(m+1) and isprime(m+3) and isprime(m+7) and isprime(m+9) then print(n); fi: od: quit
  • Mathematica
    Select[ Range[ 1, 10000, 3 ], PrimeQ[ 10*#+1 ] && PrimeQ[ 10*#+3 ] && PrimeQ[ 10*#+7 ] && PrimeQ[ 10*#+9 ]& ]
    Select[Range[15000], And @@ PrimeQ /@ ({1, 3, 7, 9} + 10#) &] (* Ray Chandler, Jan 12 2007 *)
  • PARI
    p=2;q=3;r=5;forprime(s=7,1e5,if(s-p==8 && r-p==6 && q-p==2 && p%10==1, print1(p", ")); p=q;q=r;r=s) \\ Charles R Greathouse IV, Mar 21 2013
    
  • Perl
    use ntheory ":all"; my @s = map { ($-1)/10 } sieve_prime_cluster(10,1e9, 2,6,8); say for @s; # _Dana Jacobsen, May 04 2017

Formula

a(n) = 3*A014561(n) + 1. - Zak Seidov, Sep 21 2009

A023202 Primes p such that p + 8 is also prime.

Original entry on oeis.org

3, 5, 11, 23, 29, 53, 59, 71, 89, 101, 131, 149, 173, 191, 233, 263, 269, 359, 389, 401, 431, 449, 479, 491, 563, 569, 593, 599, 653, 683, 701, 719, 743, 761, 821, 911, 929, 983, 1013, 1031, 1061, 1109, 1163, 1193, 1223, 1229, 1283, 1289, 1319, 1373, 1439
Offset: 1

Views

Author

Keywords

Comments

All terms > 3 are congruent to 5 mod 6 (observation by Zak Seidov in SeqFan). Thus each corresponding p + 8 is congruent to 1 mod 6. - Rick L. Shepherd, Mar 25 2023

Crossrefs

Programs

A086140 Primes p such that three (the maximum number) primes occur between p and p+12.

Original entry on oeis.org

5, 7, 11, 97, 101, 1481, 1867, 3457, 5647, 15727, 16057, 16061, 19417, 19421, 21011, 22271, 43777, 43781, 55331, 79687, 88807, 101107, 144161, 165701, 166841, 195731, 201821, 225341, 247601, 257857, 266677, 268811, 276037, 284737, 326141, 340927
Offset: 1

Views

Author

Labos Elemer, Jul 29 2003

Keywords

Comments

p+12 must be a prime. - Harvey P. Dale, Jun 11 2015
A086140 is the union of A022006 and A022007. By merging the two b-files I have extended the current b-file up to n=10000 (nearly n=20000 would have been possible). I add a comparison (see Links) between the frequency of prime 5-tuples and an asymptotic approximation, which is unproven but likely to be true, and based on a conjecture first published by Hardy and Littlewood in 1923. Twins, triples and quadruplets are treated as well. - Gerhard Kirchner, Dec 07 2016

Examples

			There are two types of prime 5-tuples, and both are represented in this sequence. (11, 13, 17, 19, 23) is a prime 5-tuple of the form (p, p+2, p+6, p+8, p+12), so 11 is in the sequence, and (97, 101, 103, 107, 109) is a prime 5-tuple of the form (p, p+4, p+6, p+10, p+12), so 97 is in the sequence. - _Michael B. Porter_, Dec 19 2016
		

Crossrefs

Cf. A031930, A046133, A086139, A086136, A022006, A022007, A001359 (twins), A007529 (triples), A007530 (quadruplets).

Programs

  • Mathematica
    cp[x_, y_] := Count[Table[PrimeQ[i], {i, x, y}], True] {d=12, k=0}; Do[s=Prime[n]; s1=Prime[n+1]; If[PrimeQ[s+d]&&Equal[cp[s+1, s+d-1], 3], k=k+1; Print[s]], {n, 1, 100000}]
    (* Second program: *)
    Transpose[Select[Partition[Prime[Range[30000]],5,1],#[[5]]-#[[1]] == 12&]][[1]] (* Harvey P. Dale, Jun 11 2015 *)

A257124 Initial members of prime septuplets.

Original entry on oeis.org

11, 5639, 88799, 165701, 284729, 626609, 855719, 1068701, 1146779, 6560999, 7540439, 8573429, 11900501, 15760091, 17843459, 18504371, 19089599, 21036131, 24001709, 25658441, 39431921, 42981929, 43534019, 45002591, 67816361, 69156539, 74266259, 79208399, 80427029, 84104549, 86818211, 87988709, 93625991, 124066079
Offset: 1

Views

Author

Tim Johannes Ohrtmann, Apr 16 2015

Keywords

Crossrefs

Initial members of all of the first prime k-tuplets:
twin primes: A001359.
prime triples: A007529 out of A022004, A022005.
prime quadruplets: A007530.
prime 5-tuples: A086140 out of A022007, A022006.
prime sextuplets: A022008.
prime septuplets: this sequence out of A022009, A022010.
prime octuplets: A065706 out of A022011, A022012, A022013.
prime nonuplets: A257125 out of A022547, A022548, A022545, A022546.
prime decaplets: A257127 out of A027569, A027570.
prime 11-tuplets: A257129 out of A213646, A213647.
prime 12-tuplets: A257131 out of A213601, A213645.
prime 13-tuplets: A257135 out of A214947, A257137, A257138, A257139, A257140, A257141.
prime 14-tuplets: A257166 out of A257167, A257168.
prime 15-tuplets: A257169 out of A257304, A257305, A257306, A257307.
prime 16-tuplets: A257308 out of A257369, A257370.
prime 17-tuplets: A257373 out of A257374, A257375, A257376, A257377.
Cf. A343637 (distance from 10^n to the next septuplet).
Cf. A100418.

Formula

Disjoint union of A022009 and A022010. - M. F. Hasler, Aug 04 2021

A078847 Initial term in sequence of four consecutive primes separated by 3 consecutive differences each <= 6 (i.e., when d = 2, 4 or 6) and forming pattern = [2, 4, 6]; short notation = [246] d-pattern.

Original entry on oeis.org

17, 41, 227, 347, 641, 1091, 1277, 1427, 1487, 1607, 2687, 3527, 3917, 4001, 4127, 4637, 4787, 4931, 8231, 9461, 10331, 11777, 12107, 13901, 14627, 20747, 21557, 23741, 25577, 26681, 26711, 27737, 27941, 28277, 29021, 31247, 32057, 32297
Offset: 1

Views

Author

Labos Elemer, Dec 11 2002

Keywords

Comments

Subsequence of A022004. - R. J. Mathar, Feb 10 2013
a(n) + 12 is the greatest term in the sequence of 4 consecutive primes with 3 consecutive gaps 2, 4, 6. - Muniru A Asiru, Aug 03 2017

Examples

			17, 17+2 = 19, 17+2+4 = 23, 17+2+4+6 = 29 are consecutive primes.
		

Crossrefs

Cf. analogous prime quadruple sequences with various possible {2, 4, 6}-difference-patterns in brackets: A007530[242], A078847[246], A078848[264], A078849[266], A052378[424], A078850[426], A078851[462], A078852[466], A078853[624], A078854[626], A078855[642], A078856[646], A078857[662], A078858[664], A033451[666].
Cf. A190814[2,4,6,8], A190817[2,4,6,8,10], A190819[2,4,6,8,10,12], A190838[2,4,6,8,10,12,14]

Programs

  • Mathematica
    d = Differences[Prime[Range[10000]]]; Prime[Flatten[Position[Partition[d, 3, 1], {2, 4, 6}]]] (* T. D. Noe, May 23 2011 *)
    Transpose[Select[Partition[Prime[Range[10000]],4,1],Differences[#] == {2,4,6}&]][[1]] (* Harvey P. Dale, Aug 07 2013 *)

Formula

Primes p=prime(i) such that prime(i+1) = p+2, prime(i+2) = p+2+4, prime(i+3) = p+2+4+6.

Extensions

Listed terms verified by Ray Chandler, Apr 20 2009
Additional cross references from Harvey P. Dale, May 10 2014

A257125 Initial members of prime 9-tuplets (or nonuplets).

Original entry on oeis.org

7, 11, 13, 17, 1277, 88789, 113143, 113147, 855709, 74266249, 182403491, 226449521, 252277007, 408936947, 521481197, 626927443, 910935911, 964669609, 1042090781, 1116452627, 1209950867, 1422475909, 1459270271, 1645175087, 2117861719, 2335215973, 2558211559, 2843348351, 2873599429, 2966003057, 3447123283, 3947480417
Offset: 1

Views

Author

Tim Johannes Ohrtmann, Apr 16 2015

Keywords

Comments

Primes prime(m) such that prime(m+8) = prime(m) + 30. - Zak Seidov, Jul 06 2015

Crossrefs

Initial members of all of the first prime k-tuplets:
twin primes: A001359.
prime triples: A007529 out of A022004, A022005.
prime quadruplets: A007530.
prime 5-tuples: A086140 out of A022007, A022006.
prime sextuplets: A022008.
prime septuplets: A257124 out of A022009, A022010.
prime octuplets: A065706 out of A022011, A022012, A022013.
prime nonuplets: this sequence out of A022547, A022548, A022545, A022546.
prime decaplets: A257127 out of A027569, A027570.
prime 11-tuplets: A257129 out of A213646, A213647.
prime 12-tuplets: A257131 out of A213601, A213645.
prime 13-tuplets: A257135 out of A214947, A257137, A257138, A257139, A257140, A257141.
prime 14-tuplets: A257166 out of A257167, A257168.
prime 15-tuplets: A257169 out of A257304, A257305, A257306, A257307.
prime 16-tuplets: A257308 out of A257369, A257370.
prime 17-tuplets: A257373 out of A257374, A257375, A257376, A257377.

Programs

  • Magma
    [NthPrime(n): n in [0..2*10^4] | NthPrime(n+8) eq (NthPrime(n) + 30)]; // Vincenzo Librandi, Jul 08 2015
  • Mathematica
    {p, q, r, s, t, u, v, w, x} = Prime@ Range@ 9; lst = {}; While[p < 1000000001, If[p + 30 == x, AppendTo[lst, p]; Print@ p]; {p, q, r, s, t, u, v, w, x} = {q, r, s, t, u, v, w, x, NextPrime@ x}]; lst (* Robert G. Wilson v, Jul 06 2015 *)
    Select[Partition[Prime[Range[5 10^6]],9,1],#[[1]]+30==#[[9]]&][[;;,1]] (* The program generates the first 10 terms of the sequence. To generate more, increase the Range constant. *) (* Harvey P. Dale, Jul 01 2024 *)
  • PARI
    main(size)=v=vector(size); i=0; m=1; while(iAnders Hellström, Jul 08 2015
    
Showing 1-10 of 112 results. Next