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.

A134117 Primes p such that q-p = 36, where q is the next prime after p.

Original entry on oeis.org

9551, 12853, 14107, 15823, 18803, 22193, 22307, 22817, 24281, 27143, 28351, 29881, 32261, 40387, 42863, 45083, 45197, 46771, 46957, 47981, 50461, 57601, 60041, 60457, 62423, 65993, 66301, 68171, 69073, 69557, 71597, 72577, 72823, 73783
Offset: 1

Views

Author

Rick L. Shepherd, Oct 08 2007

Keywords

Crossrefs

Programs

  • Mathematica
    Select[Partition[Prime[Range[10000]],2,1],#[[2]]-#[[1]]==36&][[All,1]] (* Harvey P. Dale, Aug 27 2019 *)
  • PARI
    is(n)=nextprime(n+1)==n+36 && isprime(n) \\ Charles R Greathouse IV, Sep 14 2015

Formula

a(n) >> n log^2 n. - Charles R Greathouse IV, Sep 14 2015

A271347 Primes p such that p + 38 is also prime.

Original entry on oeis.org

3, 5, 23, 29, 41, 59, 71, 89, 101, 113, 173, 191, 233, 239, 269, 293, 311, 359, 383, 401, 419, 449, 461, 503, 509, 563, 569, 593, 653, 701, 719, 773, 821, 839, 881, 929, 953, 971, 983, 1013, 1031, 1049, 1091, 1163, 1193, 1259, 1283, 1289
Offset: 1

Views

Author

Karl V. Keller, Jr., Apr 04 2016

Keywords

Comments

A134118 is a subsequence of this sequence.

Examples

			3 such that 3 + 38 = 41 is also prime.
5 such that 5 + 38 = 43 is also prime.
		

Crossrefs

Programs

  • Mathematica
    Select[Prime[Range[250]], PrimeQ[# + 38] &] (* Alonso del Arte, Apr 05 2016 *)
  • PARI
    lista(nn) = forprime(p=2, nn, if(ispseudoprime(p+38), print1(p, ", "))); \\ Altug Alkan, Apr 05 2016
  • Python
    from sympy import isprime
    for i in range(3, 2001,2):
      if isprime(i) and isprime(i+38): print (i,end=', ')
    

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

A320717 Indices of primes followed by a gap (distance to next larger prime) of 38.

Original entry on oeis.org

3302, 4052, 4154, 4743, 5093, 5229, 5782, 5902, 6131, 6406, 6802, 7145, 7164, 7399, 7718, 7789, 8303, 8782, 9237, 9957, 10073, 10431, 10465, 10541, 10549, 10580, 10981, 11244, 11818, 11853, 12147, 12574, 13094, 13237, 13286, 13337, 13435, 13669, 13906, 14186, 14270, 14301, 14380, 14397
Offset: 1

Views

Author

M. F. Hasler, Oct 19 2018

Keywords

Comments

Indices of the primes listed in A134118.

Crossrefs

Cf. A029707, A029709 (analog for gaps 2 & 4), A320701, A320702, ... A320720 (analog for gaps 6, 8, ..., 44), A116493 (gap 70), A116496 (gap 100), A116497 (gap 200), A116495 (gap 210).
Equals A000720 o A134118.
Indices of 38's in A001223.
Row 19 of A174349.

Programs

  • PARI
    A(N=100,g=38,p=2,i=primepi(p)-1,L=List())={forprime(q=1+p,,i++; if(p+g==p=q, listput(L,i); N--||break));Vec(L)} \\ returns the list of first N terms of the sequence

Formula

a(n) = A000720(A134118(n)).
Showing 1-4 of 4 results.