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.

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A356175 Numbers k such that k^2 + {1,3,7,13,163} are prime.

Original entry on oeis.org

2, 4, 10, 14290, 64390, 74554, 83464, 93460, 132304, 238850, 262630, 277630, 300206, 352600, 376190, 404954, 415180, 610340, 806180, 984686, 1025650, 1047050, 1106116, 1382860, 2014624, 2440714, 2525870, 2538344, 2760026, 2826380, 3145600, 3508586, 3715156
Offset: 1

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Author

Jean-Marc Rebert, Jul 28 2022

Keywords

Comments

For 14 <= m <= 999 and k <= A356110(31) = 8069560, the number of sets of primes of the form k^2 + {1,3,7,13,m} is the greatest for m = 163. There are 51 such terms. See b-file.
All terms are 2 or 4 modulo 6.

Examples

			2 is a term since 2^2 + {1,3,7,13,163} = {5,7,11,17,167} are all primes.
		

Crossrefs

Programs

  • Maple
    q:= k-> andmap(j-> isprime(k^2+j), [1, 3, 7, 13, 163]):
    select(q, [$0..1000000])[];  # Alois P. Heinz, Jul 28 2022
  • Mathematica
    Select[Range[4*10^6], AllTrue[#^2 + {1, 3, 7, 13, 163}, PrimeQ] &] (* Amiram Eldar, Jul 28 2022 *)
  • PARI
    is(k)=my(v=[1,3,7,13,163],ok=1);for(i=1,#v,if(!isprime(k^2+v[i]),ok=0;break));ok
    
  • Python
    from sympy import isprime
    def ok(n): return all(isprime(n*n+i) for i in {1,3,7,13,163})
    print([k for k in range(10**6) if ok(k)]) # Michael S. Branicky, Jul 28 2022
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