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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A096785 Primes of form 4k+1 which are the sum of two consecutive composite numbers.

Original entry on oeis.org

17, 29, 41, 53, 89, 97, 101, 109, 113, 137, 149, 173, 181, 197, 229, 233, 241, 257, 269, 281, 293, 317, 337, 349, 353, 373, 389, 401, 409, 433, 449, 461, 509, 521, 557, 569, 577, 593, 601, 617, 641, 653, 677, 701, 709, 761, 769, 773, 797, 809, 821, 829, 853
Offset: 1

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Author

Lekraj Beedassy, Jul 09 2004

Keywords

Crossrefs

Subsequence of A060254. See A096786 for values 2n. See A096675 for n values.

Programs

  • Mathematica
    Do[If[PrimeQ[2*n+1]&&Equal[Mod[s, 4], 1]&&!PrimeQ[n]&&!PrimeQ[n+1], Print[2*n+1]], {n, 1, 1000}] (* Labos Elemer *)
    2Select[ Range[450], PrimeQ[ # ] == PrimeQ[ # + 1] == PrimeQ[2# + 1, GaussianIntegers -> True] == False && PrimeQ[2# + 1] == True &] + 1 (* Robert G. Wilson v, Jul 11 2004 *)
  • PARI
    nextcomposite(k)=if(k<3,4,if(isprime(k),k+1,k));
    {m=440;n=4;while(nKlaus Brockhaus, Jul 11 2004

Formula

Equals 1 + 2*A096786.

Extensions

Corrected and extended by Klaus Brockhaus, Rick L. Shepherd and Ray Chandler, Jul 10 2004
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