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 1-6 of 6 results.

A329158 Let P1>=3, P2, P3 be consecutive primes, with P3-P2=2. a(n)=(P2+P3)/12 when P2-P1 sets a record.

Original entry on oeis.org

1, 2, 5, 25, 87, 192, 500, 1158, 1668, 4217, 4713, 5955, 17127, 28905, 61838, 76967, 96147, 139725, 260342, 1061923, 1205080, 4663498, 8871842, 11732765, 32534740, 42313103, 77638122, 92523718, 282054523, 728833340, 2940948542, 3344803093, 11810906035
Offset: 1

Views

Author

Hugo Pfoertner, Nov 06 2019

Keywords

Comments

6*a(n)-1, 6*a(n)+1 are twin primes such that the prime gap immediately preceding 6*a(n)-1 sets a record. The corresponding gap lengths are provided in A329159.

Crossrefs

Programs

  • PARI
    p1=3;p2=5;r=0;forprime(p3=7,1e9,if(p3-p2==2,d=p2-p1;if(d>r,r=d;print1((p2+p3)/12,", ")));p1=p2;p2=p3)

A329159 2*a(n) are the lengths of record prime gaps immediately preceding twin primes.

Original entry on oeis.org

1, 2, 3, 5, 6, 11, 14, 15, 17, 20, 24, 26, 30, 35, 39, 42, 45, 50, 66, 68, 74, 75, 89, 98, 104, 107, 117, 123, 144, 159, 165, 180, 183, 192, 195
Offset: 1

Views

Author

Hugo Pfoertner, Nov 06 2019

Keywords

Comments

The corresponding locations are provided in A329158. The gap 2 -> 3 before the pair 3, 5 is excluded.

Crossrefs

Programs

  • PARI
    p1=3;p2=5;r=0;forprime(p3=7,1e9,if(p3-p2==2,d=p2-p1;if(d>r,r=d;print1(d/2,", ")));p1=p2;p2=p3)

Extensions

a(31)-a(34) from Jinyuan Wang, Mar 01 2020
a(35) from David Trimas, Jul 26 2023

A329160 Let P1>=5, P2, P3 be consecutive primes, with P2-P1=2. a(n)=(P1+P2)/12 when P3-P2 sets a record.

Original entry on oeis.org

1, 5, 23, 33, 87, 278, 495, 1293, 2027, 2690, 4245, 6773, 13283, 24938, 28893, 44270, 67475, 139708, 224922, 315893, 971000, 1723960, 3319792, 6228255, 7013717, 13194622, 25321985, 31864375, 32163975, 65155398, 86090027, 381175405, 452803425
Offset: 1

Views

Author

Hugo Pfoertner, Nov 08 2019

Keywords

Comments

6*a(n)-1, 6*a(n)+1 are twin primes such that the prime gap immediately following 6*a(n)+1 sets a record. The corresponding gap lengths are provided in A329161.

Examples

			See A329161.
		

Crossrefs

Programs

  • PARI
    p1=5; p2=7; r=0; forprime(p3=11, 1e9, if(p2-p1==2, d=p3-p2; if(d>r, r=d; print1((p1+p2)/12, ", "))); p1=p2; p2=p3)

A329161 2*a(n) are the lengths of record prime gaps immediately following twin primes.

Original entry on oeis.org

2, 3, 5, 6, 9, 12, 14, 15, 17, 21, 26, 27, 29, 30, 35, 41, 45, 50, 59, 60, 63, 71, 74, 75, 84, 92, 96, 98, 104, 110, 125, 129, 144, 155, 156, 165, 180, 201, 204, 207
Offset: 1

Views

Author

Hugo Pfoertner, Nov 08 2019

Keywords

Comments

The corresponding locations are provided in A329160, starting at the initial pair 5, 7.

Examples

			a(1) = 2 because the prime gap after 5, 7 has length 11 - 7 = 2*a(1) = 4,
a(2) = 3 because the prime gap after 29,31 has length 37 - 31 = 2*a(2) = 6, with location given by 6*A329160(2) = 30 +- 1. The gaps before all have length 4 (11,13 -> 17), (17,19 -> 23).
		

Crossrefs

Programs

  • PARI
    p1=5; p2=7; r=0; forprime(p3=11, 1e9, if(p2-p1==2, d=p3-p2; if(d>r, r=d; print1(d/2, ", "))); p1=p2; p2=p3)

Extensions

a(39)-a(40) from Jinyuan Wang, Mar 01 2020

A329164 Let P1, P2, P3, P4 be consecutive primes, with P2-P1=P4-P3=2. a(n)=(P1+P2)/12 when P3-P2 sets a new record.

Original entry on oeis.org

1, 23, 322, 495, 3407, 8113, 28893, 139708, 716182, 2497092, 5130198, 5761777, 7315173, 13194622, 145995245, 201544467, 417649822, 566513637, 833667068, 2266818768, 4710228962, 5186737183, 5192311957, 7454170028, 9853412390, 11817808908
Offset: 1

Views

Author

Hugo Pfoertner, Nov 07 2019

Keywords

Comments

Position of record gaps with no primes bounded by consecutive pairs of twin primes. The length of the corresponding record gaps (P3-P1)/6 is given by A329165.
In the neighborhood of a(15), the growth of this sequence seems to change notably. See the plot2 graph in the links. Does this signify anything important? - Peter Munn, Aug 01 2025

Examples

			Values of P1, P2, P3, P4 corresponding to record gaps:
  P3-P1 P1   P2   P3   P4                   a(n)
   6     5    7   11   13        (5+7)/12 =   1
  12   137  139  149  151    (137+139)/12 =  23
  18  1931 1933 1949 1951  (1931+1933)/12 = 322
  30  2969 2971 2999 3001  (2969+2971)/12 = 495
		

Crossrefs

Programs

  • PARI
    p1=3;p2=5;p3=7;r=0;forprime(p4=11,1e9,if(p2-p1==2&&p4-p3==2,d=p3-p2;if(d>r,r=d;print1((p1+p2)/12,", ")));p1=p2;p2=p3;p3=p4)

A329250 Let P1, P2, P3, P4 be consecutive primes, with P2 - P1 = P4 - P3 = 2. a(n) = (P1 + P2)/12 for the first occurrence of (P3 - P1)/6 = n.

Original entry on oeis.org

1, 23, 322, 1573, 495, 3407, 10498, 85067, 8113, 112912, 166302, 28893, 189052, 510548, 598532, 812752, 139708, 716182, 2582073, 4576458, 2497092, 5130198, 5761777, 25381573, 7315173, 20200532, 40629683, 33185292, 69948743, 38771927, 13194622
Offset: 1

Views

Author

Hugo Pfoertner, Nov 09 2019

Keywords

Comments

Position of first occurrence of a gap of length P3 - P2 = 6*n - 2 containing no primes, bounded by twin primes (P1,P2) below and (P3,P4) above.

Examples

			a(4) = 1573, because the 4 primes P1 = 6*1573 - 1 = 9437, P2 = 6*1573 + 1 = 9439, P3 = P1 + 6*4 = 9461, P4 = 9463 produce the first occurrence of the gap P3 - P2 = 9461 - 9439 = 6*4 - 2 = 22. See also example in A329164.
		

Crossrefs

Programs

  • PARI
    my(v=vector(31),p1=3,p2=5,p3=7,r=0,d);forprime(p4=11,5e8,if(p2-p1==2&&p4-p3==2,d=(p3-p1)/6;if(v[d]==0,v[d]=(p1+p2)/12));p1=p2;p2=p3;p3=p4);v
Showing 1-6 of 6 results.