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 1-4 of 4 results.

A330853 First occurrences of gaps between primes 6k+1: gap sizes.

Original entry on oeis.org

6, 12, 18, 30, 24, 54, 42, 36, 48, 60, 78, 66, 72, 84, 90, 96, 114, 102, 162, 108, 126, 120, 132, 150, 138, 144, 174, 168, 156, 192, 204, 180, 198, 252, 270, 216, 222, 186, 228, 210, 240, 282, 246, 234, 276, 264, 258, 312, 330, 318, 288, 306, 294, 336, 300, 378
Offset: 1

Views

Author

Alexei Kourbatov, Apr 27 2020

Keywords

Comments

Contains A268925 as a subsequence.
Conjecture: the sequence is a permutation of all positive multiples of 6, i.e., all positive terms of A008588.
Conjecture: a(n) = O(n). See arXiv:2002.02115 (sect.7) for discussion.

Examples

			The first primes of the form 6k+1 are 7 and 13, so a(1)=13-7=6. The next prime 6k+1 is 19, and the gap 19-13=6 already occurred, so a new term is not added to the sequence. The next prime 6k+1 is 31, and the gap 31-19=12 is occurring for the first time; therefore a(2)=12.

Links

Crossrefs

Cf. A002476, A014320, A058320, A330854 (primes 6k+1 preceding the first-occurrence gaps), A330855 (primes 6k+1 at the end of the first-occurrence gaps).

Programs

  • PARI
    isFirstOcc=vector(9999,j,1); s=7; forprime(p=13,1e8, if(p%6!=1,next); g=p-s; if(isFirstOcc[g/6], print1(g", "); isFirstOcc[g/6]=0); s=p)

Formula

a(n) = A330855(n) - A330854(n).

A330854 Primes of the form 6k + 1 preceding the first-occurrence gaps in A330853.

Original entry on oeis.org

7, 19, 43, 241, 283, 1327, 1489, 1951, 2389, 4363, 7789, 10177, 16759, 22189, 24247, 38461, 40237, 43441, 69499, 75403, 100801, 118927, 171271, 195541, 204163, 250279, 480169, 577639, 590437, 1164607, 1207699, 1278817, 1382221, 1467937, 1526659, 1889803, 2314369
Offset: 1

Views

Author

Alexei Kourbatov, Apr 27 2020

Keywords

Comments

Subsequence of A002476. First differs from A268926 in that that sequence does not include 283; all terms of A268926 are in this sequence but many terms of this sequence are not in A268926.

Examples

			The first two primes of the form 6k + 1 are 7 and 13, so a(1) = 7. The next prime of that form is 19, and the gap 19 - 13 = 6 already occurred; so a new term is not added to the sequence. The next prime of the form 6k + 1 is 31, and the gap 31 - 19 = 12 is occurring for the first time; therefore a(2) = 19.
The gap between 241 and the next prime of the form 6k + 1 (271) is 30. So 241 is in the sequence.
Although the gap between 283 and 307 is only 24 (which is less than 30), the gap is of a size not previously encountered. So 283 is in the sequence.

Links

Crossrefs

Cf. A002476, A014320, A058320, A330853 (gap sizes), A330855.

Programs

  • PARI
    isFirstOcc=vector(9999,j,1); s=7; forprime(p=13,1e8, if(p%6!=1,next); g=p-s; if(isFirstOcc[g/6], print1(s", "); isFirstOcc[g/6]=0); s=p)

Formula

a(n) = A330855(n) - A330853(n).

A268927 Primes 6k + 1 at the end of the maximal gaps in A268925.

Original entry on oeis.org

13, 31, 61, 271, 1381, 4423, 7867, 22273, 24337, 38557, 40351, 69661, 480343, 1164799, 1207903, 1468189, 1526929, 3976003, 11962963, 14466967, 19097593, 30098239, 39895771, 198389797, 303644749, 393202651, 485949787, 680676709, 1917215533, 3868901233, 4899890383, 6957510319, 7599383353
Offset: 1

Views

Author

Alexei Kourbatov, Feb 15 2016

Keywords

Comments

Subsequence of A002476 and A330855.
A268925 lists the corresponding record gap sizes. See more comments there.

Examples

			The first two primes of the form 6k+1 are 7 and 13, so a(1)=13. The next prime of this form is 19; the gap 19-13 is not a record so nothing is added to the sequence. The next prime of this form is 31 and the gap 31-19=12 is a new record, so a(2)=31.

Links

Crossrefs

Cf. A002476, A268925, A268926, A330853, A330855.

Programs

  • PARI
    re=0; s=7; forprime(p=13, 1e8, if(p%6!=1, next); g=p-s; if(g>re, re=g; print1(p", ")); s=p)

Formula

a(n) = A268925(n) + A268926(n). - Alexei Kourbatov, Jun 21 2020

A334545 Primes of the form 6k - 1 at the end of first-occurrence gaps in A334543.

Original entry on oeis.org

11, 41, 131, 227, 383, 557, 1151, 1787, 4337, 6449, 7433, 8363, 9137, 12893, 35729, 37781, 58889, 59879, 97787, 105863, 130769, 148667, 153887, 180959, 220151, 328271, 402761, 407153, 416849, 542441, 780587, 1138367, 1294571, 1444463, 1463837, 1604951
Offset: 1

Views

Author

Alexei Kourbatov, May 05 2020

Keywords

Comments

Subsequence of A007528. Contains A268930 as a subsequence. First differs from A268930 at a(5)=383.
A334543 lists the corresponding gap sizes; see more comments there.

Examples

			The first two primes of the form 6k-1 are 5 and 11, so we have a(1)=11. The next primes of this form are 17, 23, 29; the gaps 17-11 = 23-17 = 29-23 have size 6 which already occurred before; so nothing is added to the sequence. The next prime of this form is 41 and the gap size 41-29=12 has not occurred before, so a(2)=41.

Links

Crossrefs

Cf. A007528, A014320, A058320, A268930, A330855, A334543, A334544.

Programs

  • PARI
    isFirstOcc=vector(9999,j,1); s=5; forprime(p=11,1e8,if(p%6!=5,next); g=p-s; if(isFirstOcc[g/6], print1(p", "); isFirstOcc[g/6]=0); s=p)

Formula

a(n) = A334543(n) + A334544(n).
Showing 1-4 of 4 results.

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