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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A023189 Conjecturally, number of infinitely recurring prime patterns of width 2n-1.

Original entry on oeis.org

1, 1, 1, 3, 4, 4, 14, 13, 16, 48, 55, 50, 173, 148, 147, 665, 580, 559, 1920, 1447, 1975, 6240, 4228, 5689, 15764, 17562, 14332, 46207, 39071, 35317, 172311, 134752, 110758, 381384, 299971, 479935, 1154568, 733900, 1027967, 2581763, 2636545, 2333308, 8369027, 5516720, 6043194
Offset: 1

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Of the patterns counted by A023192, the number of those that start and end with a prime. - Sean A. Irvine, May 27 2019

Examples

			From _Jon E. Schoenfield_, May 17 2024: (Start)
The table below lists every (conjecturally) infinitely recurring prime pattern of width 2n-1 for n = 1..7. Each p represents a prime; each c represents a composite.
.
  n  2n-1  a(n)  prime patterns
  -  ----  ----  --------------------------------------------------
  1     1     1  p
  2     3     1  pcp
  3     5     1  pcccp
  4     7     3  pcccccp, pcpcccp, pcccpcp
  5     9     4  pcccccccp, pcpcccccp, pcccccpcp, pcpcccpcp
  6    11     4  pcccccccccp, pcccpcccccp, pcccccpcccp, pcccpcpcccp
  7    13    14  pcccccccccccp, pcpcccccccccp, pcccpcccccccp,
                 pcccccpcccccp, pcccccccpcccp, pcccccccccpcp,
                 pcpcccpcccccp, pcpcccccpcccp, pcccpcpcccccp,
                 pcccpcccccpcp, pcccccpcpcccp, pcccccpcccpcp,
                 pcpcccpcpcccp, pcccpcpcccpcp
(End)
		

Crossrefs

Extensions

Name edited by Jon E. Schoenfield, May 17 2024
a(43)-a(45) from Pontus von Brömssen, Aug 25 2025

A023190 Conjecturally, maximum number of primes in an infinitely-recurring prime pattern of width 2*n-1.

Original entry on oeis.org

1, 2, 2, 3, 4, 4, 5, 5, 6, 6, 7, 6, 7, 8, 8, 9, 10, 10, 11, 10, 11, 12, 12, 12, 13, 14, 13, 14, 15, 15, 16, 16, 16, 17, 17, 18, 18, 18, 19, 19, 20, 20, 21, 21, 21, 22, 22, 23, 23, 23, 24, 24, 24, 24, 24, 25, 25, 26, 26, 26, 27, 27, 27, 28, 28, 29, 29, 29, 30, 30
Offset: 1

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Comments

Of all the patterns in A023192 (i.e. infinitely-recurring prime patterns) for length 2*n-1, consider those starting and ending with "p". This sequence gives the maximal count of "p"'s in any of those patterns. The companion sequence A023191, gives the number of patterns achieving that maximum. - Sean A. Irvine, May 27 2019

Examples

			a(3) concerns patterns of length 5. Of the 10 potential patterns (ccccc, ccccp, cccpc, ccpcc, cpccc, pcccc, ccpcp, cpcpc, pcpcc, pcccp), only pcccp starts and ends with a "p", and it contains 2 "p"'s, so a(3) = 2, and A023191(3) = 1. - _Sean A. Irvine_, May 27 2019
		

Crossrefs

Extensions

More terms from Thomas J Engelsma web page added by Martin Raab, Oct 31 2021
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