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 11 results. Next

A031928 Lower prime of a difference of 10 between consecutive primes.

Original entry on oeis.org

139, 181, 241, 283, 337, 409, 421, 547, 577, 631, 691, 709, 787, 811, 829, 919, 1021, 1039, 1051, 1153, 1171, 1249, 1399, 1471, 1627, 1699, 1723, 1801, 1879, 2017, 2029, 2053, 2089, 2143, 2521, 2647, 2719, 2731, 2767, 2887, 2917, 3001, 3109, 3361, 3517, 3547, 3571, 3583, 3709, 3769, 3823, 3853, 4201, 4219, 4231, 4243, 4261, 4273, 4327, 4339, 4363, 4483, 4663, 4861, 4909, 4957, 5011, 5179, 5323, 5581, 5659, 5701, 5791, 5869, 6079, 6091
Offset: 1

Views

Author

Lekraj Beedassy, Jul 23 2003

Keywords

Comments

Conjecture: The sequence is infinite and for every n, a(n+1) < a(n)^(1+1/n). Namely, a(n)^(1/n) is a strictly decreasing function of n (see comments at A248855). - Jahangeer Kholdi and Farideh Firoozbakht, Nov 29 2014

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(7000) | NextPrime(p)-p eq 10]; // Bruno Berselli, Apr 09 2013
    
  • Mathematica
    Transpose[Select[Partition[Prime[Range[800]], 2, 1], #[[2]] - #[[1]] == 10&]] [[1]] (* Harvey P. Dale, Oct 02 2014 *)
    p = Prime@Range@800; p[[Flatten@Position[Differences@p, 10]]] (* Hans Rudolf Widmer, Aug 28 2022 *)
  • PARI
    forprime(p=o=1,1e4,10+o==(o=p)&&print1(p-10",")) \\ M. F. Hasler, Mar 10 2017

Formula

a(n) = prime(A320703(n)). - R. J. Mathar, Apr 30 2024

Extensions

Edited by Labos Elemer, Jul 25 2003

A052380 a(n) = D is the smallest distance (D) between 2 non-overlapping prime twins differing by d=2n; these twins are [p,p+d] or [p+D,p+D+d] and p > 3.

Original entry on oeis.org

6, 6, 6, 12, 12, 12, 18, 18, 18, 24, 24, 24, 30, 30, 30, 36, 36, 36, 42, 42, 42, 48, 48, 48, 54, 54, 54, 60, 60, 60, 66, 66, 66, 72, 72, 72, 78, 78, 78, 84, 84, 84, 90, 90, 90, 96, 96, 96, 102, 102, 102, 108, 108, 108, 114, 114, 114, 120, 120, 120, 126, 126, 126, 132
Offset: 1

Views

Author

Labos Elemer, Mar 13 2000

Keywords

Comments

For d=D the quadruple of primes becomes a triple: [p,p+d],[p+d,p+2d].
Without the p > 3 condition, a(1)=2.
The starter prime p, is followed by a prime d-pattern of [d,D-d,d], where D-d=a(n)-2n is 4,2 or 0; these d-patterns are as follows: [2,4,2], [4,2,4], [6,6], [8,4,8], [10,2,10], [12,12], etc.
All terms of this sequence have digital root 3, 6 or 9. - J. W. Helkenberg, Jul 24 2013
a(n+1) is also the number of the circles added at the n-th iteration of the pattern generated by the construction rules: (i) At n = 0, there are six circles of radius s with centers at the vertices of a regular hexagon of side length s. (ii) At n > 0, draw a circle with center at each boundary intersection point of the figure of the previous iteration. The pattern seems to be the flower of life except at the central area. See illustration. - Kival Ngaokrajang, Oct 23 2015

Examples

			n=5, d=2n=10, the minimal distance for 10-twins is 12 (see A031928, d=10) the smallest term in A053323. It occurs first between twins of [409,419] and [421,431]; see 409 = A052354(1) = A052376(1) = A052381(5).
		

Crossrefs

Programs

  • Mathematica
    Table[2 n + 4 - 2 Mod[n + 2, 3], {n, 66}] (* Michael De Vlieger, Oct 23 2015 *)
  • PARI
    vector(200, n, n--; 6*(n\3+1)) \\ Altug Alkan, Oct 23 2015

Formula

a(n) = 6*ceiling(n/3) = 6*ceiling(d/6) = D = D(n).
a(n) = 2n + 4 - 2((n+2) mod 3). - Wesley Ivan Hurt, Jun 30 2013
a(n) = 6*A008620(n-1). - Kival Ngaokrajang, Oct 23 2015

A052354 Least prime in A031928 (lesser of 10-twins) whose distance to the next 10-twin is 6*n.

Original entry on oeis.org

409, 691, 787, 547, 2053, 139, 4861, 283, 181, 25087, 337, 709, 2917, 829, 14197, 919, 3001, 33589, 2767, 421, 8221, 1879, 5179, 1249, 1471, 10141, 5011, 20533, 4483, 54091, 13249, 4663, 27883, 5869, 41443, 8599, 23311, 9049, 40699, 82591, 3109, 5323, 44917, 11971
Offset: 2

Views

Author

Labos Elemer, Mar 07 2000

Keywords

Comments

a(n) = p determines a prime quadruple [p, p+10, p+6n, p+6n+10] with difference pattern [10, 6n-10, 10].
The smallest distance between 10-twins [A052380(5)] is 12, while its increment is 6.
a(n) = p is the smallest of A031928 followed by the next 10-twin after a 6n distance.

Examples

			a(3) = 691 results in [691, 701, 709, 719] quadruple and [10, 8, 10] difference pattern without primes in the median gap.
a(11) = 25087 yields [25087, 25097, 25153, 25163] and [10, 56, 10] with 5 primes in the middle gap.
		

Crossrefs

Programs

  • Mathematica
    seq[m_] := Module[{p = Prime[Range[m]], d, i, pp, dd, j}, d = Differences[p]; i = Position[d, 10] // Flatten; pp = p[[i]]; dd = Differences[pp]/6 - 1; j = TakeWhile[FirstPosition[dd, #] & /@ Range[Max[dd]] // Flatten, ! MissingQ[#] &]; pp[[j]]]; seq[10000] (* Amiram Eldar, Mar 05 2025 *)~
  • PARI
    list(len) = {my(s = vector(len), c = 0, p1 = 2, q1 = 0, q2, d); forprime(p2 = 3, , if(p2 == p1 + 10, q2 = p1; if(q1 > 0, d = (q2 - q1)/6 - 1; if(d <= len && s[d] == 0, c++; s[d] = q1; if(c == len, return(s)))); q1 = q2); p1 = p2);} \\ Amiram Eldar, Mar 05 2025

Extensions

Name and offset corrected by Amiram Eldar, Mar 05 2025

A053325 First differences of A031932.

Original entry on oeis.org

180, 24, 456, 66, 24, 90, 456, 174, 264, 192, 318, 66, 210, 120, 66, 120, 84, 570, 84, 102, 54, 30, 276, 354, 324, 72, 84, 180, 156, 24, 336, 270, 114, 666, 324, 150, 90, 324, 96, 24, 126, 186, 108, 126, 24, 150, 162, 528, 186, 54, 120, 90, 300, 456, 120, 150
Offset: 1

Views

Author

Labos Elemer, Mar 06 2000

Keywords

Crossrefs

Programs

  • Mathematica
    Differences[Transpose[Select[Partition[Prime[Range[1500]],2,1], Last[#]- First[#] == 14&]][[1]]] (* Harvey P. Dale, Aug 24 2012 *)

A053321 First differences of A031924.

Original entry on oeis.org

8, 16, 6, 8, 12, 10, 48, 20, 6, 10, 6, 60, 18, 6, 6, 8, 60, 22, 14, 6, 10, 50, 10, 60, 38, 16, 6, 8, 16, 6, 8, 6, 40, 6, 24, 50, 6, 18, 190, 6, 24, 6, 14, 22, 20, 30, 34, 6, 14, 6, 58, 6, 30, 6, 8, 52, 8, 30, 40, 6, 66, 20, 40, 50, 10, 48, 12, 8, 36, 84, 6, 6, 24, 84, 40, 6, 66, 14, 24
Offset: 1

Views

Author

Labos Elemer, Mar 06 2000

Keywords

Crossrefs

Programs

  • GAP
    P:=Filtered([1..2100],IsPrime);;
    P1:=List(Filtered([1..Length(P)-1],i->P[i+1]-P[i]=6),k->P[k]);;
    a:=List([1..Length(P1)-1],i->P1[i+1]-P1[i]);; Print(a); # Muniru A Asiru, Dec 23 2018
  • Mathematica
    With[{p = Prime[Range[330]]}, Differences[p[[Position[Differences[p], 6] // Flatten]]]] (* Amiram Eldar, Mar 10 2025 *)

A053322 First differences of A031926.

Original entry on oeis.org

270, 30, 12, 48, 30, 12, 192, 18, 18, 24, 18, 150, 18, 54, 126, 54, 30, 180, 66, 84, 36, 12, 162, 90, 156, 24, 150, 60, 30, 30, 186, 72, 78, 54, 36, 42, 102, 36, 30, 102, 30, 168, 12, 228, 42, 132, 78, 18, 162, 408, 60, 234, 168, 192, 108, 120, 18, 210, 174, 120, 90
Offset: 1

Views

Author

Labos Elemer, Mar 06 2000

Keywords

Comments

Minimal value 12 is for n = 3, 6, 22, 43, 90, 123, 125, 135, 144, 147, 201, 255, 276, 287, 310, 338, 350. - Zak Seidov, Jun 12 2017

Crossrefs

Programs

  • Mathematica
    With[{p = Prime[Range[1000]]}, Differences[p[[Position[Differences[p], 8] // Flatten]]]] (* Amiram Eldar, Mar 10 2025 *)

A053324 First differences of A031930.

Original entry on oeis.org

12, 256, 42, 110, 42, 136, 200, 204, 36, 70, 152, 40, 12, 20, 178, 80, 22, 78, 180, 30, 198, 102, 48, 132, 42, 156, 150, 122, 18, 102, 22, 68, 72, 16, 152, 60, 100, 272, 58, 90, 20, 298, 12, 140, 130, 12, 110, 76, 42, 120, 48, 110, 64, 158, 88, 320, 100, 174, 50
Offset: 1

Views

Author

Labos Elemer, Mar 06 2000

Keywords

Crossrefs

Programs

  • Mathematica
    Differences[Select[Partition[Prime[Range[1000]],2,1],#[[2]]-#[[1]]==12&][[;;,1]]] (* Harvey P. Dale, Sep 28 2024 *)

A053326 First differences of A031934.

Original entry on oeis.org

102, 180, 108, 30, 342, 210, 318, 252, 18, 42, 210, 414, 54, 456, 54, 402, 258, 342, 258, 756, 126, 78, 42, 450, 84, 576, 588, 66, 366, 228, 420, 246, 366, 240, 354, 90, 240, 156, 150, 198, 510, 246, 96, 828, 156, 60, 36, 870, 180, 114, 54, 660, 600, 522, 330
Offset: 1

Views

Author

Labos Elemer, Mar 06 2000

Keywords

Crossrefs

Programs

  • Mathematica
    With[{p = Prime[Range[2000]]}, Differences[p[[Position[Differences[p], 16] // Flatten]]]] (* Amiram Eldar, Mar 10 2025 *)

A053327 First differences of A031936.

Original entry on oeis.org

546, 190, 122, 378, 154, 248, 342, 358, 942, 86, 270, 214, 50, 40, 140, 100, 30, 326, 150, 274, 528, 218, 222, 78, 52, 38, 540, 192, 42, 40, 26, 162, 262, 308, 570, 348, 184, 456, 200, 244, 498, 62, 378, 1488, 52, 50, 42, 160, 60, 780, 78, 42, 128, 22, 270, 66
Offset: 1

Views

Author

Labos Elemer, Mar 06 2000

Keywords

Crossrefs

Programs

  • Mathematica
    With[{p = Prime[Range[2000]]}, Differences[p[[Position[Differences[p], 18] // Flatten]]]] (* Amiram Eldar, Mar 10 2025 *)

A052376 Primes followed by a [10,2,10] prime difference pattern of A001223.

Original entry on oeis.org

409, 1039, 2017, 2719, 3571, 4219, 4231, 4261, 4327, 6079, 6121, 6679, 6781, 8209, 11047, 11149, 11959, 12241, 15277, 19531, 19687, 21577, 21589, 26881, 27529, 28087, 28297, 29389, 30829, 30859, 31069, 32401, 42061, 45307, 47797, 48109
Offset: 1

Views

Author

Labos Elemer, Mar 22 2000

Keywords

Comments

Subsequence of lesser terms of 10-twins (A031928).
Start primes of quadruples consisting of two consecutive 10-twins of prime which are in minimal distance [minD = A052380(10/2) = 12].
First term of this sequence is 409 = A052381(5).

Examples

			p=1039 begins [1039,1049,1051,1061] prime quadruple with the appropriate difference pattern: [10,2,10]=[d,D-d,d], so d=10, D=12.
		

Crossrefs

Programs

  • Mathematica
    {p, q, r, s} = {2, 3, 5, 7}; lst = {}; While[p < 50000, If[ Differences[{p, q, r, s}] == {10, 2, 10}, AppendTo[lst, p]]; {p, q, r, s} = {q, r, s, NextPrime@ s}]; lst (* Robert G. Wilson v, Jul 15 2015 *)

Formula

a(n)=p, a prime which begins a [p, p+d, p+D, p+D+d]=[p, p+10, p+12, p+22] prime quadruple.
a(n) = A259025(n)-11. - Robert G. Wilson v, Jul 15 2015
Showing 1-10 of 11 results. Next