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 1-3 of 3 results.

A105652 Numbers k such that p1=2k+3, p2=4k+5 and p3=6k+7 are all prime.

Original entry on oeis.org

0, 2, 17, 104, 134, 152, 164, 167, 299, 362, 584, 617, 647, 764, 827, 1109, 1139, 1277, 1517, 1529, 1532, 2129, 2222, 2399, 2474, 2612, 2789, 2924, 3074, 3179, 3344, 3419, 3482, 3809, 3839, 3842, 3932, 4007, 4082, 4094, 4142, 4259, 4262, 4322, 4469, 4544
Offset: 1

Views

Author

Zak Seidov, Apr 16 2005

Keywords

Comments

Except for 0, all terms == 2 or 14 (mod 15). - Robert Israel, Jun 08 2018

Crossrefs

Programs

  • Magma
    [n: n in [0..5000] | IsPrime(2*n+3) and IsPrime(4*n+5) and IsPrime(6*n+7)]; // Vincenzo Librandi, Nov 13 2010
  • Maple
    select(k -> andmap(isprime, [2*k+3,4*k+5,6*k+7]), [0, seq(seq(15*i+j,j=[2,14]),i=0..1000)]); # Robert Israel, Jun 08 2018

Formula

a(n) = (A174734(n)-3)/2. - Robert Israel, Jun 08 2018

A237189 Numbers k such that k+1, 2k+1, 3k+1, 4k+1 are all prime.

Original entry on oeis.org

330, 1530, 3060, 4260, 4950, 6840, 10830, 15390, 18120, 23010, 25410, 26040, 31770, 33300, 40110, 41490, 45060, 49830, 53880, 59340, 65850, 70140, 73770, 78540, 88740, 95460, 96930, 109470, 111720, 112620, 117720, 131310, 133200, 134730, 135300, 150150, 165900
Offset: 1

Views

Author

Alex Ratushnyak, Feb 04 2014

Keywords

Comments

A subsequence of A064238.
All terms are divisible by 30, and b(n)=a(n)/30 begins: 11, 51, 102, 142, 165, 228, 361, 513, 604, 767, 847, 868, 1059, 1110, 1337, 1383, 1502, 1661, 1796, 1978, 2195, ...

Crossrefs

Programs

  • Python
    import sympy
    from sympy import isprime
    for n in range(0,100000,2):
        if isprime(n+1) and isprime(2*n+1) and isprime(3*n+1) and isprime(4*n+1):
            print(str(n), end=',')

Formula

a(n) = 2*(A105653(n) + 1) = 2*A124409(n). - Hugo Pfoertner, May 03 2021

A105655 Numbers k such that p1=2k+3, p2=4k+5, p3=6k+7, p4=8k+9, p5=10k+11 and p6=12k+13 are all prime.

Original entry on oeis.org

12704, 13019, 105524, 256409, 966839, 1707509, 1944494, 2309999, 2478629, 3132674, 3836069, 3976769, 4112429, 4532324, 5499584, 5920004, 6610484, 7390844, 8552249, 10739504, 11120339, 12231449, 12338129, 13243229, 16467254
Offset: 1

Views

Author

Zak Seidov, Apr 16 2005

Keywords

Crossrefs

Programs

  • Magma
    [n: n in [0..10000000]|IsPrime(2*n+3) and IsPrime(4*n+5) and IsPrime(6*n+7) and IsPrime(8*n+9) and IsPrime(10*n+11)and IsPrime(12*n+13)] // Vincenzo Librandi, Dec 16 2010
  • Mathematica
    With[{r1=Range[2,12,2],r2=Range[3,13,2]},Select[Range[16500000],And@@PrimeQ[# r1+r2]&]] (* Harvey P. Dale, Jan 31 2011 *)
Showing 1-3 of 3 results.