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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A094897 If 4*n+1 is not prime and 4*n+3 is prime then a(n)=4*n+3, else a(n)=0.

Original entry on oeis.org

3, 0, 11, 0, 0, 23, 0, 0, 0, 0, 0, 47, 0, 0, 59, 0, 67, 71, 0, 79, 83, 0, 0, 0, 0, 0, 107, 0, 0, 0, 0, 127, 131, 0, 0, 0, 0, 0, 0, 0, 163, 167, 0, 0, 179, 0, 0, 191, 0, 0, 0, 0, 211, 0, 0, 223, 227, 0, 0, 239, 0, 0, 251, 0, 0, 263, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 307, 311, 0, 0, 0, 0, 331, 0
Offset: 0

Views

Author

Roger L. Bagula, Jun 14 2004

Keywords

Crossrefs

Cf. A045751, A095278, A094896.

Programs

  • Magma
    [IsPrime(4*n+3) and not IsPrime(4*n+1) select 4*n+3 else 0:n in [0..85]]; // Marius A. Burtea, Nov 15 2019
  • Maple
    A094897 := proc(n)
    if not isprime(4*n+1) and isprime(4*n+3) then
        4*n+3;
    else
        0;
    end if;
end proc:
seq(A094897(n),n=0..86) ; # R. J. Mathar, Nov 15 2019
  • Mathematica
    a=Table[If[PrimeQ[4*n+1]==False&&PrimeQ[4*n+3]==True, 4*n+3, 0], {n, 0, 200}]

A094898 This sequence needs a proper name.

Original entry on oeis.org

7, 0, 0, 17, 0, 0, 0, 0, 0, 41, 0, 0, 0, 0, 0, 0, 71, 0, 0, 83, 0, 0, 0, 0, 101, 0, 0, 113, 0, 0, 0, 131, 0, 0, 0, 0, 0, 0, 0, 0, 167, 0, 0, 0, 0, 0, 0, 0, 197, 0, 0, 0, 0, 0, 0, 227, 0, 233, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 281, 0, 0, 0, 0, 0, 0, 311, 0, 317, 0, 0, 0, 0, 0, 0, 0, 0, 353, 0, 0, 0, 0
Offset: 1

Views

Author

Roger L. Bagula, Jun 14 2004

Keywords

Crossrefs

Cf. A094896, A094897.

Programs

  • Mathematica
    a=Table[If[PrimeQ[4*n+1]==True&&PrimeQ[4*n+3]==False, 1, 0], {n, 0, 200}]
b=Table[If[PrimeQ[4*n+1]==False&&PrimeQ[4*n+3]==True, 1, 0], {n, 0, 200}]
d=Table[If[PrimeQ[a[[n]]*(4*n+1)+b[[n]]*(4*n+3)]==True, a[[n]]*(4*n+1)+b[[n]]*(4*n+3), 0], {n, 1, 200}]
  • PARI
    av(terms) = my(v=[]); for(n=0, oo, if(ispseudoprime(4*n+1) && !ispseudoprime(4*n+3), v=concat(v, [1]), v=concat(v, [0])); if(#v==terms, break)); v
bv(terms) = my(v=[]); for(n=0, oo, if(!ispseudoprime(4*n+1) && ispseudoprime(4*n+3), v=concat(v, [1]), v=concat(v, [0])); if(#v==terms, break)); v
a(n) = my(avv=av(n), bvv=bv(n), x=avv[#avv], y=bvv[#bvv], val=x*(4*n+1)+y*(4*n+3)); if(ispseudoprime(val), return(val), return(0)) \\ Felix Fröhlich, Jul 03 2021; Program adapted from Mathematica code
Showing 1-2 of 2 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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