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 1-9 of 9 results.

A049545 Primes p such that x^13 = 2 has a solution mod p.

Original entry on oeis.org

2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 59, 61, 67, 71, 73, 83, 89, 97, 101, 103, 107, 109, 113, 127, 137, 139, 149, 151, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293
Offset: 1

Views

Author

Keywords

Comments

Complement of A059245 relative to A000040. - Vincenzo Librandi, Sep 13 2012

Examples

			0^13 == 2 (mod 2). 2^13 == 2 (mod 3). 2^13 == 2 (mod 5). 2^13 == 2 (mod 7). 7^13 == 2 (mod 11). 2^13 == 2 (mod 13). 15^13 == 2 (mod 17). 14^13 == 2 (mod 19). 18^13 == 2 (mod 23). 14^13 == 2 (mod 29). 4^13 == 2 (mod 31). 20^13 == 2 (mod 37). 36^13 == 2 (mod 41). 22^13 == 2 (mod 43). - _R. J. Mathar_, Jul 20 2025
		

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(400) | exists(t){x : x in ResidueClassRing(p) | x^13 eq 2}]; // Vincenzo Librandi, Sep 13 2012
  • Mathematica
    ok[p_]:= Reduce[Mod[x^13- 2, p] == 0, x, Integers]=!=False; Select[Prime[Range[200]], ok] (* Vincenzo Librandi, Sep 13 2012 *)

A268753 Primes congruent to 1 mod 13.

Original entry on oeis.org

53, 79, 131, 157, 313, 443, 521, 547, 599, 677, 859, 911, 937, 1093, 1171, 1223, 1249, 1301, 1327, 1483, 1613, 1847, 1873, 1951, 2003, 2029, 2081, 2237, 2341, 2393, 2549, 2731, 2861, 2887, 2939, 3121, 3251, 3329, 3407, 3433, 3511, 3719, 3797, 3823, 4057, 4421, 4447, 4603, 4733, 4759, 4889, 4967, 4993, 5227, 5279
Offset: 1

Views

Author

Alexei Kourbatov, Feb 12 2016

Keywords

Comments

The first 45 terms, up to 4057, coincide with A059245. Then a(46)=4421 occurs in this sequence, while A059245(46)=4447.

Examples

			53 is the first prime of the form 13k + 1, therefore a(1)=53.
		

Crossrefs

Cf. A059245 (x^13 = 2 has no solution mod prime p).

Programs

  • Magma
    [p: p in PrimesUpTo(5300) | p mod 13 in {1} ]; // Vincenzo Librandi, Feb 13 2016
  • Mathematica
    Select[Prime@ Range@ 700, Mod[#, 13] == 1 &] (* Michael De Vlieger, Feb 12 2016 *)
  • PARI
    forprime(p=2, 1e4, if(p%13==1, print1(p", ")))
    
  • PARI
    forprimestep(p=53,1e4,26,print1(p", ")) \\ Charles R Greathouse IV, Mar 11 2020
    

Formula

a(n) ~ 12n log n. - Charles R Greathouse IV, Mar 11 2020

A140371 Primes of the form 26k + 7.

Original entry on oeis.org

7, 59, 137, 163, 241, 293, 397, 449, 631, 683, 709, 761, 787, 839, 1021, 1151, 1229, 1307, 1489, 1567, 1619, 1697, 1723, 1801, 1879, 1931, 2087, 2113, 2243, 2269, 2347, 2399, 2477, 2503, 2633, 2659, 2711, 2789, 2971, 3023, 3049, 3257, 3361, 3413, 3491, 3517
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Jun 14 2008

Keywords

Crossrefs

Programs

Extensions

Edited by R. J. Mathar, Jun 16 2008

A140373 Primes of the form 26*n+11.

Original entry on oeis.org

11, 37, 89, 167, 193, 271, 349, 401, 479, 557, 661, 739, 947, 1051, 1103, 1129, 1181, 1259, 1493, 1571, 1597, 1753, 1831, 1987, 2039, 2143, 2221, 2273, 2351, 2377, 2663, 2689, 2741, 2767, 2819, 2897, 3001, 3079, 3209, 3313, 3391, 3469, 3547, 3677, 3833
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Jun 14 2008

Keywords

Comments

Also primes of the form 13*n+11. - N. J. A. Sloane, Jul 11 2008

Crossrefs

Programs

Extensions

Edited by R. J. Mathar, Jun 16 2008

A140375 Primes of the form 26n+23.

Original entry on oeis.org

23, 101, 127, 179, 257, 283, 439, 491, 569, 647, 673, 751, 829, 881, 907, 1063, 1193, 1297, 1427, 1453, 1531, 1583, 1609, 1973, 1999, 2129, 2207, 2311, 2389, 2441, 2467, 2753, 2857, 2909, 3169, 3221, 3299, 3533, 3559, 3637, 3767, 3793, 3923, 4001, 4027
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Jun 14 2008

Keywords

Comments

Also primes congruent to 10 mod 13. - N. J. A. Sloane, Jul 11 2008

Crossrefs

Programs

Extensions

Edited by R. J. Mathar, Jun 16 2008

A140372 Primes of the form 26k + 9.

Original entry on oeis.org

61, 113, 139, 191, 269, 347, 373, 503, 607, 659, 919, 971, 997, 1049, 1153, 1231, 1283, 1361, 1439, 1543, 1621, 1699, 1777, 1907, 1933, 2011, 2063, 2089, 2141, 2297, 2531, 2557, 2609, 2687, 2713, 2791, 2843, 2999, 3181, 3259, 3389, 3467, 3571, 3623, 3701
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Jun 14 2008

Keywords

Comments

Also primes of the form 13k + 9. - N. J. A. Sloane, Jul 11 2008

Crossrefs

Programs

Extensions

Edited by R. J. Mathar, Jun 16 2008

A140374 Primes of the form 26k + 15.

Original entry on oeis.org

41, 67, 197, 223, 353, 379, 431, 457, 509, 587, 613, 691, 743, 769, 821, 977, 1237, 1289, 1367, 1471, 1523, 1549, 1601, 1627, 1783, 1861, 1913, 2017, 2069, 2251, 2381, 2459, 2693, 2719, 2797, 2927, 2953, 3083, 3109, 3187, 3343, 3499, 3733, 3863, 3889
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Jun 14 2008

Keywords

Crossrefs

Programs

Extensions

Edited by R. J. Mathar, Jun 16 2008

A140376 Nonprimes of the form 26n+1.

Original entry on oeis.org

1, 27, 105, 183, 209, 235, 261, 287, 339, 365, 391, 417, 469, 495, 573, 625, 651, 703, 729, 755, 781, 807, 833, 885, 963, 989, 1015, 1041, 1067, 1119, 1145, 1197, 1275, 1353, 1379, 1405, 1431, 1457, 1509, 1535, 1561, 1587, 1639, 1665, 1691, 1717, 1743
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Jun 14 2008

Keywords

Crossrefs

Programs

  • Magma
    [a: n in [0..80] | not IsPrime(a) where a is 26*n+1]; // Vincenzo Librandi, Mar 22 2014
  • Mathematica
    Select[26 Range[0, 100] + 1, ! PrimeQ@# &] (* Vincenzo Librandi, Mar 22 2014 *)

Extensions

Edited by R. J. Mathar, Jun 16 2008

A275773 Primes p congruent to 1 modulo 13 such that x^13 = 2 has a solution modulo p.

Original entry on oeis.org

4421, 4733, 5669, 5981, 8581, 9413, 10453, 11597, 13963, 14327, 14951, 19267, 22699, 22907, 23557, 25117, 25819, 26417, 28627, 31799, 32579, 35491, 37441, 41549, 44773, 44851, 45553, 46619, 46957, 48179, 49297, 49921, 49999, 50207, 52859, 53639, 60217, 64403
Offset: 1

Views

Author

Felix Fröhlich, Aug 08 2016

Keywords

Comments

Intersection of A049545 and A268753.
These are the counterexamples mentioned in the Sep 12 2012 comment from Bruno Berselli in A059245.

Examples

			4421 is in the sequence since it is prime, it is congruent to 1 (mod 13), and x^13 == 2 (mod 4421) has the solution x = 162. - _Michael B. Porter_, Aug 26 2016
		

Crossrefs

Programs

  • Mathematica
    Quiet@ Select[Prime@ Range[10^4], And[Mod[#, 13] == 1, IntegerQ@ PowerMod[2, 1/13, #]] &] (* Michael De Vlieger, Aug 10 2016 *)
  • PARI
    forprime(p=1, 1e6, if(Mod(p, 13)==1 && ispower(Mod(2, p), 13), print1(p, ", ")))
Showing 1-9 of 9 results.