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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A245304 Numbers m such that m+1, m+3, m+7, m+9 and m+13 are all primes.

Original entry on oeis.org

4, 10, 100, 1480, 16060, 19420, 21010, 22270, 43780, 55330, 144160, 165700, 166840, 195730, 201820, 225340, 247600, 268810, 326140, 347980, 361210, 397750, 465160, 518800, 536440, 633460, 633790, 661090, 768190, 795790, 829720, 857950, 876010, 958540
Offset: 1

Views

Author

Reinhard Zumkeller, Jul 18 2014

Keywords

References

  • W. SierpiƄski, 250 Problems in Elementary Number Theory. New York: American Elsevier, 1970. Problem #82, variant.

Crossrefs

Cf. A010051, A022006, A245305, A007811, subsequence of A125855.

Programs

  • Haskell
    a245304 n = a245304_list !! (n-1)
    a245304_list = map (pred . head) $ filter (all (== 1) . map a010051') $
       iterate (zipWith (+) [1, 1, 1, 1, 1]) [1, 3, 7, 9, 13]
    
  • Magma
    [n: n in [0..10^6] | IsPrime(n+1) and IsPrime(n+3) and IsPrime(n+7) and IsPrime(n+9) and IsPrime(n+13)]; // Vincenzo Librandi, Jun 15 2015
  • Mathematica
    Select[Range[10^6],AllTrue[#+{1,3,7,9,13},PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, May 07 2015 *)
  • PARI
    forprime(p=2, 10^7, m=p-1; if(isprime(m+3)&&isprime(m+7)&&isprime(m+9)&&isprime(m+13), print1(m", "))) \\ Jens Kruse Andersen, Jul 18 2014
    

Formula

a(n) = A022006(n)-1. - Jens Kruse Andersen, Jul 18 2014

A350825 Number of prime 5-tuples with initial member (A086140) between 10^(n-1) and 10^n.

Original entry on oeis.org

2, 2, 1, 4, 12, 44, 256, 1062, 5838
Offset: 1

Views

Author

M. F. Hasler, Mar 01 2022

Keywords

Comments

"Between 10^(n-1) and 10^n" is equivalent to saying "with n digits".
For n = 1 and n = 2, the last term of the last 5-tuple in that range (cf EXAMPLE) has one digit more than the initial term.
Terms a(1)-a(9) computed from b-files a(1..10000) for A022006 and A022007.

Examples

			a(1) = 2 because there are just two single-digit primes to start a prime 5-tuple, namely 5 = A022006(1) and 7 = A022007(1).
a(2) = 2 because 11 = A022006(2) and 97 = A022007(2) are the only two two-digit primes to start a prime 5-tuple.
a(3) = 1 because there is only one three-digit prime to start a prime 5-tuple, namely 101 = A022006(3).
Then there are a(4) = 4 four-digit primes, 1481, 1867, 3457 and 5647, which start a prime 5-tuple.
		

Crossrefs

Cf. A086140 (initial members p of prime quintuplets), A022006, A022007 (idem, specifically for patterns (p, p+2, ...) resp. (p, p+4, ...)).
Cf. A350826, A350827, A350828: similar for sextuplets, septuplets and octuplets.

Programs

  • PARI
    (D(v)=v[^1]-v[^-1])( [setsearch(A086140, 10^n, 1) | n<-[0..9]] ) \\ where A086140 is a vector of at least 7221 terms of that sequence.

A078947 Primes p such that the differences between the 5 consecutive primes starting with p are (2,4,6,6).

Original entry on oeis.org

41, 641, 1091, 4001, 9461, 26681, 26711, 44531, 79811, 103991, 110921, 112571, 172421, 223241, 276821, 289841, 290021, 317771, 373181, 381371, 434921, 450881, 493121, 602081, 678761, 788351, 834131, 907211, 974861, 1076501, 1081121, 1097891, 1200371, 1409531, 1426151
Offset: 1

Views

Author

Labos Elemer, Dec 19 2002

Keywords

Comments

Equivalently, primes p such that p, p+2, p+6, p+12 and p+18 are consecutive primes.

Examples

			641 is in the sequence since 641, 643 = 641 + 2, 647 = 641 + 6, 653 = 641 + 12 and 659 = 641 + 18 are consecutive primes.
		

Crossrefs

Programs

  • Mathematica
    Select[Partition[Prime[Range[50000]], 5, 1], Differences[#] == {2, 4, 6, 6} &][[;;, 1]] (* Amiram Eldar, Feb 21 2025 *)
  • 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 == 6, print1(p1, ", ")); p1 = p2; p2 = p3; p3 = p4; p4 = p5);} \\ Amiram Eldar, Feb 21 2025

Formula

a(n) == 11 (mod 30). - Amiram Eldar, Feb 21 2025

Extensions

Edited by Dean Hickerson, Dec 20 2002

A201074 Initial primes in prime 5-tuples (p, p+2, p+6, p+8, p+12) preceding the maximal gaps in A201073.

Original entry on oeis.org

5, 11, 101, 1481, 22271, 55331, 536441, 661091, 1461401, 1615841, 5527001, 11086841, 35240321, 53266391, 72610121, 92202821, 117458981, 196091171, 636118781, 975348161, 1156096301, 1277816921, 1347962381, 2195593481, 3128295551
Offset: 1

Views

Author

Alexei Kourbatov, Nov 26 2011

Keywords

Comments

Prime quintuplets (p, p+2, p+6, p+8, p+12) are one of the two types of densest permissible constellations of 5 primes. Maximal gaps between quintuplets of this type are listed in A201073; see more comments there.

Examples

			The initial four gaps of 6, 90, 1380, 14580 (starting at p=5, 11, 101, 1481) form an increasing sequence of records. Therefore a(1)=5, a(2)=11, a(3)=101, and a(4)=1481. The next gap is smaller, so a new term is not added.
		

Crossrefs

Cf. A022006 (prime 5-tuples p, p+2, p+6, p+8, p+12), A201073, A233432.

A233432 Primes p in prime 5-tuples (p, p+2, p+6, p+8, p+12) at the end of the maximal gaps in A201073.

Original entry on oeis.org

11, 101, 1481, 16061, 43781, 144161, 633461, 768191, 1573541, 1917731, 5928821, 11664551, 35930171, 54112601, 73467131
Offset: 1

Views

Author

Alexei Kourbatov, Dec 09 2013

Keywords

Comments

Prime quintuplets (p, p+2, p+6, p+8, p+12) are one of the two types of densest permissible constellations of 5 primes. Maximal gaps between quintuplets of this type are listed in A201073; see more comments there.

Examples

			The initial four gaps of 6, 90, 1380, 14580 (ending at p=11, 101, 1481, 16061) form an increasing sequence of records. Therefore a(1)=11, a(2)=101, a(3)=1481 and a(4)=16061. The next gap is not a record, so a new term is not added.
		

Crossrefs

A270998 Table read by rows: list of prime 5-tuples of the form (p, p+2, p+6, p+8, p+12).

Original entry on oeis.org

5, 7, 11, 13, 17, 11, 13, 17, 19, 23, 101, 103, 107, 109, 113, 1481, 1483, 1487, 1489, 1493, 16061, 16063, 16067, 16069, 16073, 19421, 19423, 19427, 19429, 19433, 21011, 21013, 21017, 21019, 21023, 22271, 22273, 22277, 22279, 22283, 43781, 43783, 43787, 43789, 43793
Offset: 1

Views

Author

Arkadiusz Wesolowski, Jul 12 2016

Keywords

Comments

A prime 5-tuple is a constellation of five successive primes with distance 12, and is of the form (p, p+2, p+6, p+8, p+12) or (p, p+4, p+6, p+10, p+12).
Initial members p (other than 5) of prime 5-tuples of the form (p, p+2, p+6, p+8, p+12) are congruent to 11 or 101 (mod 210).
Also called prime 5-tuples of the first kind.

Crossrefs

Programs

  • Magma
    lst:=[]; for p in [5..43781 by 2] do if p eq 5 xor p mod 210 in {11, 101} then if IsPrime(p) then t:=[c: c in [p+2..p+12] | IsPrime(c)]; if #t eq 4 then lst:=lst cat [p] cat t; end if; end if; end if; end for; lst;
  • Mathematica
    m = {0, 2, 6, 8, 12}; Union@ Flatten@ Map[# + m &, Select[Prime@ Range[10^4], Times @@ Boole@ PrimeQ[# + m] == 1 &]] (* Michael De Vlieger, Jul 13 2016 *)
    Select[Partition[Prime[Range[5000]],5,1],Differences[#]=={2,4,2,4}&]// Flatten (* Harvey P. Dale, Jul 27 2020 *)

Formula

a(5*n-4) = A022006(n).

A343635 10^n + a(n) is the least (n+1)-digit prime member of a prime 5-tuple, or a(n) = 0 if no such number exists.

Original entry on oeis.org

4, 1, 1, 481, 5727, 1107, 8851, 18027, 5457, 408807, 57931, 358531, 274587, 256497, 6111627, 67437, 3246567, 1638811, 8224977, 11687221, 24556351, 3129657, 15602131, 571381, 23034391, 110598987, 26716321, 31722117, 39711931, 5046777, 81054327, 1346611, 44656587
Offset: 0

Views

Author

M. F. Hasler, Jul 17 2021

Keywords

Comments

The smallest (n+1)-digit prime 5-tuple is given by 10^n + a(n) + D, with either D = {0, 2, 6, 8, 12} or D = {0, 4, 6, 10, 12}. N = 0 is the only case where the last member of the 5-tuple has one digit more than the first member.
Numerical evidence strongly suggests the conjecture that 0 < a(n) < 10^n for all n > 0, but not even the existence of infinitely many prime 5-tuples is proved.
Some further isolated terms, due to Norman Luhn et al., giving the start of the smallest 500, 600, 700, ..., 1200 digit quintuplets of first or second type:
a(499) = min(58195471283341, 69672492141807),
a(599) = min(319491304676641, 12754947401547),
a(699) = min(2254633393747621, 209264286017367),
a(799) = min(2117758391972791, 1299258655252617),
a(899) = min(2365663735968811, 1484244113736867),
a(999) = min(3554007760224751, 3818999670116007),
a(1099) = min(26317044823878361, 15720821612555937),
a(1199) = min(20483870459152351, 7033048489975137).
Terms through a(399) may be determined by taking the minima of those in the linked tables for quintuplets by Norman Luhn et al. - Michael S. Branicky, Jul 24 2021
The first member of the quintuplets of the first type always ends in digit 1 (except for the 5-tuple (5, 7, 11, 13, 17) corresponding to a(0)), for the second type it always ends in digit 7. Therefore all a(n), n > 0, end in a digit 1 or 7, which indicates the type of the 5-tuple, i.e., the set D that has to be added to 10^n + a(n) to get the whole 5-tuple. - M. F. Hasler, Aug 04 2021

Examples

			a(0) = 4 because {5, 7, 11, 13, 17} is the smallest prime 5-tuple and it starts with the single-digit prime 10^0 + a(0) = 5 = A022006(1).
a(1) = 1 because 10^1 + 1 = 11 = A022006(2) is the 2-digit prime to start a prime 5-tuple {11, 13, 17, 19, 23}, again of the first type.
a(2) = 1 and a(3) = 481 because 10^2 + 1 = 101 = A022006(3) and 10^3 + 481 = 1481 = A022006(4) are the smallest 3-digit, resp. 4-digit, initial members of a prime 5-tuple, both again of the first type.
a(4) = 5727 because 10^4 + 5727 = 15727 = A022007(6) is the smallest 5-digit initial member of a prime 5-tuple, now of the second type.
It appears that for all n > 0, a(n) < 10^n, so that the primes are of the form 10...0XXX where XXX = a(n) and 0...0 stands for a string of zero or more digits 0.
		

Crossrefs

Cf. A022006 and A022007 (initial members of prime 5-tuples of first and second type).
Cf. A343636, A343637 (analog for sextuplets and septuplets).

Programs

  • PARI
    apply( {A343635(n,q=[1..4],i=0)=forprime(p=10^n,, (q[1+i]+12==q[i++]=p) && return(p-12-10^n); i>3 && i=0)}, [0..15]) \\ Shorter but slightly slower (?)
    
  • PARI
    apply( {A343635(n, i=ispseudoprime, q)=forprime(p=10^n,, i(p+12) && i(p+6) && (p+6 > q=nextprime(p+2)) && i(q+6) && return(p-10^n))}, [0..15])
    
  • Python
    from sympy import nextprime
    def a(n):
        p = nextprime(10**n)
        q = nextprime(p); r = nextprime(q); s = nextprime(r); t = nextprime(s)
        while p < 10**(n+1):
            if t - p == 12: return p - 10**n
            p, q, r, s, t = q, r, s, t, nextprime(t)
        return 0
    print([a(n) for n in range(14)]) # Michael S. Branicky, Jul 24 2021

A376136 Primes p_1 where products m of k = 5 consecutive primes p_1..p_k are such that only p_1 < m^(1/k).

Original entry on oeis.org

3229, 3271, 4759, 6173, 6803, 6917, 8389, 8971, 9439, 10433, 11743, 12011, 12853, 12983, 13967, 14107, 14593, 15683, 16033, 16141, 18013, 18097, 19183, 19333, 21283, 21347, 21529, 22573, 22817, 23633, 23719, 25261, 27701, 27919, 28229, 29537, 30593, 31397, 31699
Offset: 1

Views

Author

Michael De Vlieger, Sep 17 2024

Keywords

Comments

Primes p_1 are such that the difference p_2-p_1 is larger than the sum of the differences p_(j+1)-p_j for j < k.
Does not intersect A022006 or A022007.

Crossrefs

Programs

  • Mathematica
    k = 5; s = {1}~Join~Prime[Range[k - 1]]; Reap[Do[s = Append[Rest[s], Prime[i + k - 1]]; r = Surd[Times @@ s, k]; If[Count[s, _?(# < r &)] == 1, Sow[Prime[i]] ], {i, 32000}]][[-1, 1]]

A078948 Primes p such that the differences between the 5 consecutive primes starting with p are (2,6,4,2).

Original entry on oeis.org

29, 59, 269, 1289, 2129, 2789, 5639, 8999, 13679, 14549, 18119, 36779, 62129, 75989, 80669, 83219, 88799, 93479, 113159, 115769, 124769, 132749, 150209, 160079, 163979, 203309, 207509, 223829, 228509, 278489, 282089, 284729, 298679, 312929, 313979, 323369, 337859
Offset: 1

Views

Author

Labos Elemer, Dec 19 2002

Keywords

Comments

Equivalently, primes p such that p, p+2, p+8, p+12 and p+14 are consecutive primes.
All terms are congruent to 29 (mod 30). - Muniru A Asiru, Sep 04 2017

Examples

			59 is in the sequence since 59, 61 = 59 + 2, 67 = 59 + 8, 71 = 59 + 12 and 73 = 59 + 14 are consecutive primes.
		

Crossrefs

Subsequence of A078848. - R. J. Mathar, Feb 10 2013

Programs

  • GAP
    K:=26*10^7+1;; # to get all terms <= K.
    P:=Filtered([1,3..K],IsPrime);;  I:=[2,6,4,2];;
    P1:=List([1..Length(P)-1],i->P[i+1]-P[i]);;
    Q:=List(Positions(List([1..Length(P)-Length(I)],i->[P1[i],P1[i+1],P1[i+2],P1[i+3]]),I),i->P[i]); # Muniru A Asiru, Sep 04 2017
    
  • Maple
    for i from 1 to 10^5 do if [ithprime(i+1),ithprime(i+2),ithprime(i+3),ithprime(i+4)] = [ithprime(i)+2,ithprime(i)+8,ithprime(i)+12,ithprime(i)+14] then print(ithprime(i)); fi; od;  # Muniru A Asiru, Sep 04 2017
  • Mathematica
    Select[Partition[Prime[Range[26000]],5,1],Differences[#]=={2,6,4,2}&][[;;,1]] (* Harvey P. Dale, Dec 10 2024 *)
  • PARI
    list(lim) = {my(p1 = 2, p2 = 3, p3 = 5, p4 = 7); forprime(p5 = 11, lim, if(p2 - p1 == 2 && p3 - p2 == 6 && p4 - p3 == 4 && p5 - p4 == 2, print1(p1, ", ")); p1 = p2; p2 = p3; p3 = p4; p4 = p5);} \\ Amiram Eldar, Feb 21 2025

Extensions

Edited by Dean Hickerson, Dec 20 2002

A078949 Primes p such that the differences between the 5 consecutive primes starting with p are (2,6,4,6).

Original entry on oeis.org

71, 431, 2339, 2381, 5849, 6959, 27791, 32561, 41609, 45119, 46439, 48479, 51419, 54401, 63599, 78779, 81551, 106859, 115319, 130631, 138569, 143501, 153269, 166601, 183569, 196169, 204359, 229751, 246929, 266081, 279119, 321311, 326999, 350729, 357659, 362741
Offset: 1

Views

Author

Labos Elemer, Dec 19 2002

Keywords

Comments

Equivalently, primes p such that p, p+2, p+8, p+12 and p+18 are consecutive primes.

Examples

			71 is in the sequence since 71, 73 = 71 + 2, 79 = 71 + 8, 83 = 71 + 12 and 89 = 71 + 18 are consecutive primes.
		

Crossrefs

Subsequence of A078848. - R. J. Mathar, Feb 10 2013

Programs

  • Mathematica
    Select[Partition[Prime[Range[50000]], 5, 1], Differences[#] == {2, 6, 4, 6} &][[;;, 1]] (* Amiram Eldar, Feb 21 2025 *)
  • PARI
    list(lim) = {my(p1 = 2, p2 = 3, p3 = 5, p4 = 7); forprime(p5 = 11, lim, if(p2 - p1 == 2 && p3 - p2 == 6 && p4 - p3 == 4 && p5 - p4 == 6, print1(p1, ", ")); p1 = p2; p2 = p3; p3 = p4; p4 = p5);} \\ Amiram Eldar, Feb 21 2025

Formula

From Amiram Eldar, Feb 21 2025: (Start)
a(n) == 5 (mod 6).
a(n) == 11 or 29 (mod 30). (End)

Extensions

Edited by Dean Hickerson, Dec 20 2002
Previous Showing 41-50 of 75 results. Next