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.

A134121 Primes p such that q-p = 44, where q is the next prime after p.

Original entry on oeis.org

15683, 36389, 37907, 76163, 92507, 108587, 109673, 124853, 138683, 138977, 140009, 140477, 183203, 186959, 203669, 225383, 226697, 229037, 232259, 242819, 242927, 244043, 245339, 271289, 273653, 275837, 279353, 280139, 282617, 285377
Offset: 1

Views

Author

Rick L. Shepherd, Oct 08 2007

Keywords

Crossrefs

Programs

A134123 Primes p such that q-p = 48, where q is the next prime after p.

Original entry on oeis.org

28229, 73189, 86629, 105769, 106543, 113843, 137029, 156371, 157579, 163259, 166099, 168803, 172441, 177043, 177691, 179849, 180569, 183713, 203713, 204251, 206651, 220973, 222199, 226943, 229849, 233021, 234383, 240209, 242009, 260269
Offset: 1

Views

Author

Rick L. Shepherd, Oct 08 2007

Keywords

Crossrefs

Programs

  • Mathematica
    Transpose[Select[Partition[Prime[Range[25000]],2,1],Last[#]-First[#]==48&]][[1]]  (* Harvey P. Dale, Feb 07 2011 *)
    Select[Prime[Range[25000]], NextPrime[#] - # == 48 &]
  • PARI
    is(n)=nextprime(n+1)==n+48 && isprime(n) \\ Charles R Greathouse IV, Sep 14 2015

A174350 Square array: row n >= 1 lists the primes p for which the next prime is p+2n; read by antidiagonals.

Original entry on oeis.org

3, 5, 7, 11, 13, 23, 17, 19, 31, 89, 29, 37, 47, 359, 139, 41, 43, 53, 389, 181, 199, 59, 67, 61, 401, 241, 211, 113, 71, 79, 73, 449, 283, 467, 293, 1831, 101, 97, 83, 479, 337, 509, 317, 1933, 523, 107, 103, 131, 491, 409, 619, 773, 2113, 1069, 887
Offset: 1

Views

Author

Clark Kimberling, Mar 16 2010

Keywords

Comments

Every odd prime p = prime(i), i > 1, occurs in this array, in row (prime(i+1) - prime(i))/2. Polignac's conjecture states that each row contains an infinite number of indices. In case this does not hold, we can use the convention to continue finite rows with 0's, to ensure the sequence is well defined. - M. F. Hasler, Oct 19 2018
A permutation of the odd primes (A065091). - Robert G. Wilson v, Sep 13 2022

Examples

			Upper left hand corner of the array:
     3     5    11    17    29    41    59    71   101 ...
     7    13    19    37    43    67    79    97   103 ...
    23    31    47    53    61    73    83   131   151 ...
    89   359   389   401   449   479   491   683   701 ...
   139   181   241   283   337   409   421   547   577 ...
   199   211   467   509   619   661   797   997  1201 ...
   113   293   317   773   839   863   953  1409  1583 ...
  1831  1933  2113  2221  2251  2593  2803  3121  3373 ...
   523  1069  1259  1381  1759  1913  2161  2503  2861 ...
  (...)
Row 1: p(2) = 3, p(3) = 5, p(5) = 11, p(7) = 17,... these being the primes for which the next prime is 2 greater: (lesser of) twin primes A001359.
Row 2: p(4) = 7, p(6) = 13, p(8) = 19,... these being the primes for which the next prime is 4 greater: (lesser of) cousin primes A029710.
		

Crossrefs

Rows 35, 40, 45, 50, ...: A204792, A126722, A204764, A050434 (row 50), A204801, A204672, A204802, A204803, A126724 (row 75), A184984, A204805, A204673, A204806, A204807 (row 100); A224472 (row 150).
Column 1: A000230.
Column 2: A046789.

Programs

  • Mathematica
    rows = 10; t2 = {}; Do[t = {}; p = Prime[2]; While[Length[t] < rows - off + 1, nextP = NextPrime[p]; If[nextP - p == 2*off, AppendTo[t, p]]; p = nextP]; AppendTo[t2, t], {off, rows}]; Table[t2[[b, a - b + 1]], {a, rows}, {b, a}] (* T. D. Noe, Feb 11 2014 *)
    t[r_, 0] = 2; t[r_, c_] := Block[{p = NextPrime@ t[r, c - 1], q}, q = NextPrime@ p; While[ p + 2r != q, p = q; q = NextPrime@ q]; p]; Table[ t[r - c + 1, c], {r, 10}, {c, r, 1, -1}] (* Robert G. Wilson v, Nov 06 2020 *)
  • PARI
    A174350_row(g, N=50, i=0, p=prime(i+1), L=[])={g*=2; forprime(q=1+p, , i++; if(p+g==p=q, L=concat(L, q-g); N--||return(L)))} \\ Returns the first N terms of row g. - M. F. Hasler, Oct 19 2018

Formula

a(n) = A000040(A174349(n)). - Michel Marcus, Mar 30 2016

Extensions

Definition corrected and other edits by M. F. Hasler, Oct 19 2018

A273355 Numbers n such that n - 47, n - 1, n + 1, n + 47 are consecutive primes.

Original entry on oeis.org

15370470, 15462870, 18216510, 23726160, 30637050, 31054740, 38907060, 39220080, 44499900, 44678190, 60563100, 66248550, 86219910, 87095190, 87948780, 93773970, 96802860, 103011990, 105953760, 105978330, 106960410, 111219990, 116281770
Offset: 1

Views

Author

Karl V. Keller, Jr., May 20 2016

Keywords

Comments

This sequence is a subsequence of A014574 (average of twin prime pairs), A249674 (divisible by 30) and A256753.
The numbers n - 47 and n + 1 belong to A134122 (p such that p + 46 is the next prime).
The numbers n - 47 and n - 1 belong to primes p such that p and p + 48 are primes.

Examples

			15370470 is the average of the four consecutive primes 15370423, 15370469, 15370471, 15370517.
15462870 is the average of the four consecutive primes 15462823, 15462869, 15462871, 15462917.
		

Crossrefs

Cf. A014574, A077800 (twin primes), A249674, A256753.

Programs

  • PARI
    is(n)=isprime(n-1) && isprime(n+1) && precprime(n-2)==n-47 && nextprime(n+2)==n+47 \\ Charles R Greathouse IV, Jun 08 2016
  • Python
    from sympy import isprime,prevprime,nextprime
    for i in range(0,160000001,6):
      if isprime(i-1) and isprime(i+1) and prevprime(i-1) == i-47 and nextprime(i+1) == i+47: print (i,end=', ')
    
Showing 1-4 of 4 results.