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 1-5 of 5 results.

A141923 Primes congruent to 19 mod 23.

Original entry on oeis.org

19, 157, 433, 479, 571, 617, 709, 1031, 1123, 1307, 1399, 1583, 1721, 1951, 1997, 2089, 2273, 2411, 2503, 2549, 2687, 2917, 2963, 3331, 3469, 3607, 3929, 4021, 4159, 4297, 4481, 4987, 5171, 5309, 5861, 5953, 6091, 6229, 6367, 6551, 6689, 6781, 6827, 7057
Offset: 1

Views

Author

N. J. A. Sloane, Jul 11 2008

Keywords

Crossrefs

Programs

Formula

a(n) ~ 22n log n. - Charles R Greathouse IV, Jul 02 2016

A141924 Primes congruent to 20 mod 23.

Original entry on oeis.org

43, 89, 181, 227, 457, 503, 641, 733, 1009, 1193, 1423, 1607, 1699, 2113, 2251, 2297, 2389, 2711, 2803, 3079, 3217, 3539, 3631, 3677, 3769, 3907, 4091, 4229, 4597, 4643, 4919, 5011, 5333, 5471, 5563, 5701, 5839, 6299, 6529, 7127, 7219, 7541, 7817, 8093
Offset: 1

Views

Author

N. J. A. Sloane, Jul 11 2008

Keywords

Crossrefs

Programs

Formula

a(n) ~ 22n log n. - Charles R Greathouse IV, Jul 02 2016

A141925 Primes congruent to 21 mod 23.

Original entry on oeis.org

67, 113, 251, 389, 619, 757, 941, 1033, 1171, 1217, 1447, 1493, 1723, 1861, 1907, 1999, 2137, 2459, 2551, 2689, 3011, 3517, 3701, 3793, 3931, 4253, 4391, 4483, 4621, 4759, 4943, 5081, 5449, 6047, 6277, 6323, 6553, 6599, 6691, 6737, 6829, 6967, 7013, 7151
Offset: 1

Views

Author

N. J. A. Sloane, Jul 11 2008

Keywords

Crossrefs

Programs

Formula

a(n) ~ 22n log n. - Charles R Greathouse IV, Jul 02 2016

A212374 Primes congruent to 1 mod 23.

Original entry on oeis.org

47, 139, 277, 461, 599, 691, 829, 967, 1013, 1151, 1289, 1381, 1427, 1657, 1933, 1979, 2347, 2393, 2531, 3037, 3083, 3221, 3313, 3359, 3727, 3911, 4003, 4049, 4463, 4831, 4877, 4969, 5107, 5153, 5521, 5659, 5843, 5981, 6073, 6211, 6257, 6763, 6947, 7039, 7177
Offset: 1

Views

Author

Bruno Berselli, Sep 12 2012

Keywords

Comments

This sequence is not the same as A040984. First disagreement at index 34: a(34)=5153, A040984(34)=5521.

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(7200) | p mod 23 eq 1];
    
  • Maple
    select(p->irem(p, 23)=1, [ithprime(i)$i=1..1000])[]; # Alois P. Heinz, Sep 12 2012
  • Mathematica
    Select[Prime[Range[1000]], Mod[#, 23] == 1 &]
    Select[Range[1,7200,23],PrimeQ] (* Harvey P. Dale, Jul 02 2018 *)
  • PARI
    is(n)=isprime(n) && n%23==1 \\ Charles R Greathouse IV, Jul 03 2016

Formula

a(n) ~ 22n log n. - Charles R Greathouse IV, Jul 03 2016

A263769 Smallest prime q such that q == -1 (mod prime(n)-1).

Original entry on oeis.org

2, 3, 3, 5, 19, 11, 31, 17, 43, 83, 29, 71, 79, 41, 137, 103, 173, 59, 131, 139, 71, 233, 163, 263, 191, 199, 101, 211, 107, 223, 251, 389, 271, 137, 443, 149, 311, 647, 331, 859, 1423, 179, 379, 191, 587, 197, 419, 443
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Oct 25 2015

Keywords

Comments

a(n): A000040(1), A065091(1), A002145(1), A007528(1), A030433(1), A068231(1), A127576(1), A061242(1), A141857(1), A141976(1), A132236(1), A142111(1), A142198(1), A141898(1), A141926(1), A142531(1), A142004(1), A142799(1), A142068(1), A142099(1), ...
Smallest prime q such that (prime(n)^2 + q*prime(n))/(prime(n) + 1) is an integer.

Examples

			a(4) = 5 because 5 == -1 (mod prime(4)-1) and is prime.
		

Crossrefs

Programs

  • Maple
    for n from 1 to 100 do
      k:= ithprime(n)-1;
      q:= 2;
      while (1 + q) mod k <> 0 do
        q:= nextprime(q)
      od;
      A[n]:= q;
    od:
    seq(A[i],i=1..1000); # Robert Israel, Oct 26 2015
  • Mathematica
    Table[q = 2; z = Prime@ n - 1; While[Mod[q, z] != z - 1, q = NextPrime@ q]; q, {n, 59}] (* Michael De Vlieger, Oct 26 2015 *)

Extensions

Corrected and edited by Robert Israel, Oct 26 2015,
Showing 1-5 of 5 results.