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 1-6 of 6 results.

A140633 Primes of the form 7x^2+4xy+52y^2.

Original entry on oeis.org

7, 103, 127, 223, 367, 463, 487, 607, 727, 823, 967, 1063, 1087, 1303, 1327, 1423, 1447, 1543, 1567, 1663, 1783, 2143, 2287, 2383, 2503, 2647, 2767, 2887, 3343, 3463, 3583, 3607, 3727, 3823, 3847, 3943, 3967, 4327, 4423, 4447, 4567, 4663
Offset: 1

Views

Author

T. D. Noe, May 19 2008

Keywords

Comments

Discriminant=-1440. Also primes of the forms 7x^2+6xy+87y^2 and 7x^2+2xy+103y^2.
Voight proves that there are exactly 69 equivalence classes of positive definite binary quadratic forms that represent almost the same primes. 48 of those quadratic forms are of the idoneal type discussed in A139827. The remaining 21 begin at A140613 and end here. The cross-references section lists the quadratic forms in the same order as tables 1-6 in Voight's paper. Note that A107169 and A139831 are in the same equivalence class.
In base 12, the sequence is 7, 87, X7, 167, 267, 327, 347, 427, 507, 587, 687, 747, 767, 907, 927, 9X7, X07, X87, XX7, E67, 1047, 12X7, 13X7, 1467, 1547, 1647, 1727, 1807, 1E27, 2007, 20X7, 2107, 21X7, 2267, 2287, 2347, 2367, 2607, 2687, 26X7, 2787, 2847, where X is for 10 and E is for 11. Moreover, the discriminant is X00 and that all elements are {7, 87, X7, 167, 187, 247} mod 260. - Walter Kehowski, May 31 2008

Crossrefs

Programs

  • Mathematica
    Union[QuadPrimes2[7, 4, 52, 10000], QuadPrimes2[7, -4, 52, 10000]] (* see A106856 *)

A168539 Terms of A123239 which are prime in Z(i), Z(rho) and Z(sqrt(2)).

Original entry on oeis.org

11, 59, 83, 107, 131, 179, 227, 251, 347, 419, 443, 467, 491, 563, 587, 659, 683, 827, 947, 971, 1019, 1091, 1163, 1187, 1259, 1283, 1307, 1427, 1451, 1499, 1523, 1571, 1619, 1667, 1787, 1811, 1907, 1931, 1979, 2003, 2027, 2099, 2243, 2267, 2339
Offset: 1

Views

Author

A.K. Devaraj, Nov 29 2009

Keywords

Crossrefs

Programs

  • Mathematica
    MangammalQ[p_] := Block[{k = 3}, While[k > 2, k = Mod[3 k, p]]; k != 2];
    A168539 = Select[Prime[Range[350]], MangammalQ[#] && Mod[#, 24] == 11 &] (* Ray Chandler, Jul 21 2011 *)

Extensions

Corrected and extended by Ray Chandler, Jul 21 2011

A018188 The $620 prime list.

Original entry on oeis.org

5003, 5987, 6563, 9803, 10427, 11027, 11867, 16763, 19403, 22283, 22907, 24923, 25667, 29867, 35747, 40427, 40763, 41243, 42083, 49307, 54323, 54347, 57203, 57347, 66587, 67307, 73883, 78203, 84347, 104003, 112067, 121403
Offset: 1

Views

Author

N. J. A. Sloane, Jon Grantham (grantham(AT)math.uga.edu)

Keywords

Comments

Numbers are 11 mod 24.
Jon Grantham: "I strongly believe that some sub-product of these primes is a Carmichael number and a Lucas pseudoprime for the Fibonacci sequence, and also is 2 or 3 mod 5."
In particular the above conjecture implies that there is a BPSW pseudoprime smaller than 10^25286. - Charles R Greathouse IV, Sep 28 2019

Crossrefs

Subsequence of A107007 (and hence A000040).

Extensions

b-file from Charles R Greathouse IV, Aug 28 2010

A214151 Numbers k from the set == 5 (mod 6) with the property that 3^((3*k-1)/2) == 3 (mod k) and 2^((k-1)/2) == (k-1) (mod k).

Original entry on oeis.org

11, 59, 83, 107, 131, 179, 227, 251, 347, 419, 443, 467, 491, 563, 587, 659, 683, 827, 947, 971, 1019, 1091, 1163, 1187, 1259, 1283, 1307, 1427, 1451, 1499, 1523, 1571, 1619, 1667, 1787, 1811, 1907, 1931, 1979, 2003, 2027, 2099, 2243, 2267
Offset: 1

Views

Author

Alzhekeyev Ascar M, Jul 05 2012

Keywords

Comments

All composites in this sequence are 2-pseudoprimes, see A001567, and strong pseudoprimes to base 2, A001262.
The subsequence of these composites begins: 1441091, 3587553971, 4528686251, 23260036451, 47535120323, 61070250323, 90474845819, 143193768587, 162016315907, 173868807611, 180998962187, 238364070323, 285370693931, 298577370323, ...
Perhaps this sequence contains all the terms of the sequence A107007 or A168539.

Crossrefs

Subsequence of A176997.

Programs

  • Maple
    isA214151 := proc(n)
        if (n mod 6 = 5) and modp(2 &^ ((n-1)/2),n)  = n-1 and modp(3 &^ ((3*n-1)/2),n)  = 3 then
            true;
        else
            false;
        end if;
    end proc:
    for n from 5 by 6 do
        if isA214151(n) then
            print(n) ;
        end if;
    end do: # R. J. Mathar, Jul 20 2012
  • Mathematica
    Select[Range[5,2500,6],PowerMod[3,(3#-1)/2,#]==3&&PowerMod[2,(#-1)/2,#] == #-1&] (* Harvey P. Dale, Mar 14 2022 *)
  • PARI
    for(n=0, 200, b=6*n+5; if(Mod(3, b)^((3*b-1)/2)==3, if(Mod(2, b)^((b-1)/2)==b-1 , print1(b, ", "))));

A139527 Numbers n such that numbers 24n+5 are primes.

Original entry on oeis.org

0, 1, 2, 4, 6, 7, 8, 11, 12, 13, 16, 19, 21, 23, 27, 28, 29, 32, 33, 34, 39, 42, 44, 46, 49, 51, 53, 54, 57, 62, 67, 68, 71, 72, 78, 79, 81, 82, 83, 86, 89, 92, 93, 96, 97, 98, 99, 103, 106, 109, 112, 114, 116, 118, 119, 121, 123, 134, 141, 142, 144, 147, 148, 149, 153, 154
Offset: 1

Views

Author

Artur Jasinski, Apr 25 2008

Keywords

Comments

Numbers n such that:
24n+1 is prime see A111174, primes 24n+1 see A107008
24n+5 is prime see A139527, primes 24n+5 see A107003
24n+7 is prime see A139483, primes 24n+7 see A107006
24n+11 is prime A139528, primes 24n+11 see A107007
24n+13 is prime see A139529, primes 24n+13 see A139530
24n+17 is prime see A139531, primes 24n+17 see A107181
24n+19 is prime see A139532, primes 24n+19 see A141373
24n+23 is prime see A131210, primes 24n+23 see A134517

Programs

  • Mathematica
    a = {}; Do[If[PrimeQ[24 n + 5], AppendTo[a, n]], {n, 0, 200}]; a
    Select[Table[(Prime[n]-5)/24,{n,800}],IntegerQ] (* Harvey P. Dale, Feb 25 2016 *)

A273618 Numbers m = 2*k+1 where k is odd with the property that 3^k mod m = 1 and k^k mod m = 1.

Original entry on oeis.org

11, 59, 83, 107, 131, 179, 227, 251, 347, 419, 443, 467, 491, 563, 587, 659, 683, 827, 947, 971, 1019, 1091, 1163, 1187, 1259, 1283, 1307, 1427, 1451, 1499, 1523, 1571, 1619, 1667, 1787, 1811, 1907, 1931, 1979, 2003, 2027, 2099, 2243, 2267
Offset: 1

Views

Author

Alzhekeyev Ascar M, May 26 2016

Keywords

Comments

All composites in this sequence are 2-pseudoprimes, see A001567, and strong pseudoprimes to base 2, A001262.
The subsequence of these composites begins: 143193768587, 440097066011, 1188059560451, 1392770336147, 1640446291859, 2526966350771, 3639120872171, 3989703695867, 4202422108523, ....
Perhaps this sequence contains all the terms of the sequence A107007 (except 3) or A168539.

Examples

			m=131; 131=2*65+1; 3^65 mod 131 = 1 and 65^65 mod 131 = 1.
		

Crossrefs

Subsequence of A176997.

Programs

  • Maple
    filter:= proc(n) local k;
      k:= (n-1)/2;
      3 &^ k mod n = 1 and k &^ k mod n = 1
    end proc:
    select(filter, [seq(i,i=3..3000, 4)]); # Robert Israel, Nov 28 2019
  • Mathematica
    2#+1&/@Select[Range[1,1200,2],PowerMod[3,#,2#+1]==PowerMod[ #,#,2#+1] == 1&] (* Harvey P. Dale, May 05 2022 *)
Showing 1-6 of 6 results.