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.

A085759 Prime powers of the form 4n+1.

Original entry on oeis.org

1, 5, 9, 13, 17, 25, 29, 37, 41, 49, 53, 61, 73, 81, 89, 97, 101, 109, 113, 121, 125, 137, 149, 157, 169, 173, 181, 193, 197, 229, 233, 241, 257, 269, 277, 281, 289, 293, 313, 317, 337, 349, 353, 361, 373, 389, 397, 401, 409, 421, 433, 449, 457, 461, 509, 521
Offset: 1

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Author

Lekraj Beedassy, Jul 22 2003

Keywords

Crossrefs

Subsequence of A000961. A002144 is a subsequence.

Programs

  • Magma
    [1] cat [4*k+1:k in [1..140]|IsPrimePower(4*k+1)]; // Marius A. Burtea, Sep 07 2019
  • Mathematica
    {1}~Join~Select[1 + 4 Range[130], PrimePowerQ] (* Michael De Vlieger, Aug 29 2019 *)
  • PARI
    list(lim)=my(v=List([1])); forprime(p=5,lim\=1, if(p%4==1, listput(v,p))); for(e=2,logint(lim,3), forprime(p=3,sqrtnint(lim,e), if(e%2==0 || p%4==1, listput(v,p^e)))); Set(v) \\ Charles R Greathouse IV, Jul 12 2018
    

Formula

a(n) ~ 2n log n. - Charles R Greathouse IV, Jul 12 2018

Extensions

Corrected and extended by Ray Chandler, Aug 10 2003