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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A343615 Decimal expansion of P_{3,2}(5) = Sum 1/p^5 over primes == 2 (mod 3).

Original entry on oeis.org

0, 3, 1, 5, 7, 7, 1, 3, 5, 7, 1, 9, 0, 0, 3, 9, 4, 1, 9, 5, 6, 0, 3, 3, 7, 8, 0, 3, 4, 3, 7, 1, 6, 3, 9, 6, 3, 4, 7, 7, 7, 2, 9, 9, 6, 3, 8, 3, 2, 4, 8, 6, 1, 4, 5, 7, 9, 0, 2, 5, 8, 3, 4, 1, 2, 2, 8, 2, 9, 7, 5, 5, 7, 1, 9, 8, 1, 1, 7, 3, 0, 3, 9, 1, 5, 9, 6, 1, 1, 0, 7, 5, 2, 9, 7, 6, 2, 6, 2
Offset: 0

Views

Author

M. F. Hasler, Apr 22 2021

Keywords

Comments

The prime zeta modulo function P_{m,r}(s) = Sum_{primes p == r (mod m)} 1/p^s generalizes the prime zeta function P(s) = Sum_{primes p} 1/p^s.

Examples

			0.0315771357190039419560337803437163963477729963832486145790258341228297557...
		

Crossrefs

Cf. A003627 (primes 3k-1), A000584 (n^5), A085965 (PrimeZeta(5)), A021247 (1/3^5).
Cf. A343625 (same for primes 3k+1), A086035 (for primes 4k+1), A085994 (for primes 4k+3), A343612 - A343619 (P_{3,2}(2..9): same for 1/p^2, ..., 1/p^9).

Programs

  • PARI
    s=0;forprimestep(p=2,1e8,3,s+=1./p^4);s \\ For illustration: using primes up to 10^N gives about 3N+2 (= 26 for N=8) correct digits.
    
  • PARI
    A343615_upto(N=100, s=5)={localprec(N+5); digits((sumeulerrat(1/p^s)-1/3^s-PrimeZeta31(s)+1)\.1^N)[^1]} \\ see A175644 for the function PrimeZeta31, A343612 for a function PrimeZeta32

Formula

P_{3,2}(5) = P(5) - 1/3^5 - P_{3,1}(5).

A108159 Numbers n such that (initial n digits of decimal expansion of 1/243)-1 is prime.

Original entry on oeis.org

3, 160, 812
Offset: 1

Views

Author

Jason Earls, Jun 07 2005

Keywords

Crossrefs

Cf. A021247.

Programs

  • Mathematica
    Do[ If[ PrimeQ[ Floor[10^n/243 - 1]], Print[n]], {n, 8000}] (* Robert G. Wilson v, Jun 10 2005 *)
  • PARI
    for(n=1,999,if(isprime(floor(1/243*10^n)-1),print1(n",")))
Showing 1-2 of 2 results.