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.

Showing 1-9 of 9 results.

A002145 Primes of the form 4*k + 3.

Original entry on oeis.org

3, 7, 11, 19, 23, 31, 43, 47, 59, 67, 71, 79, 83, 103, 107, 127, 131, 139, 151, 163, 167, 179, 191, 199, 211, 223, 227, 239, 251, 263, 271, 283, 307, 311, 331, 347, 359, 367, 379, 383, 419, 431, 439, 443, 463, 467, 479, 487, 491, 499, 503, 523, 547, 563, 571
Offset: 1

Views

Author

Keywords

Comments

Or, odd primes p such that -1 is not a square mod p, i.e., the Legendre symbol (-1/p) = -1. [LeVeque I, p. 66]. - N. J. A. Sloane, Jun 28 2008
Primes which are not the sum of two squares, see the comment in A022544. - Artur Jasinski, Nov 15 2006
Natural primes which are also Gaussian primes. (It is a common error to refer to this sequence as "the Gaussian primes".)
Inert rational primes in the field Q(sqrt(-1)). - N. J. A. Sloane, Dec 25 2017
Numbers n such that the product of coefficients of (2n)-th cyclotomic polynomial equals -1. - Benoit Cloitre, Oct 22 2002
For p and q both belonging to the sequence, exactly one of the congruences x^2 = p (mod q), x^2 = q (mod p) is solvable, according to Gauss reciprocity law. - Lekraj Beedassy, Jul 17 2003
Also primes p that divide L((p-1)/2) or L((p+1)/2), where L(n) = A000032(n), the Lucas numbers. Union of A122869 and A122870. - Alexander Adamchuk, Sep 16 2006
Also odd primes p that divide ((p-1)!! + 1) or ((p-2)!! + 1). - Alexander Adamchuk, Nov 30 2006
Also odd primes p that divide ((p-1)!! - 1) or ((p-2)!! - 1). - Alexander Adamchuk, Apr 18 2007
This sequence is a proper subset of the set of the absolute values of negative fundamental discriminants (A003657). - Paul Muljadi, Mar 29 2008
Bernard Frénicle de Bessy discovered that such primes cannot be the hypotenuse of a Pythagorean triangle in opposition to primes of the form 4*n+1 (see A002144). - after Paul Curtz, Sep 10 2008
A079261(a(n)) = 1; complement of A145395. - Reinhard Zumkeller, Oct 12 2008
Subsequence of A007970. - Reinhard Zumkeller, Jun 18 2011
A151763(a(n)) = -1.
Primes p such that p XOR 2 = p - 2. Brad Clardy, Oct 25 2011 (Misleading in the sense that this is a formula for the super-sequence A004767. - R. J. Mathar, Jul 28 2014)
It appears that each term of A004767 is the mean of two terms of this subsequence of primes therein; cf. A245203. - M. F. Hasler, Jul 13 2014
Numbers n > 2 such that ((n-2)!!)^2 == 1 (mod n). - Thomas Ordowski, Jul 24 2016
Odd numbers n > 1 such that ((n-1)!!)^2 == 1 (mod n). - Thomas Ordowski, Jul 25 2016
Primes p such that (p-2)!! == (p-3)!! (mod p). - Thomas Ordowski, Jul 28 2016
See Granville and Martin for a discussion of the relative numbers of primes of the form 4k+1 and 4k+3. - Editors, May 01 2017
Sometimes referred to as Blum primes for their connection to A016105 and the Blum Blum Shub generator. - Charles R Greathouse IV, Jun 14 2018
Conjecture: a(n) for n > 4 can be written as a sum of 3 primes of the form 4k+1, which would imply that primes of the form 4k+3 >= 23 can be decomposed into a sum of 6 nonzero squares. - Thomas Scheuerle, Feb 09 2023

References

  • M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 870.
  • John H. Conway and Richard K. Guy, The Book of Numbers, New York: Springer-Verlag, 1996. See pp. 146-147.
  • G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers, 5th ed., Oxford Univ. Press, 1979, p. 219, th. 252.
  • W. J. LeVeque, Topics in Number Theory. Addison-Wesley, Reading, MA, 2 vols., 1956, Vol. 1, p. 66.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
  • David Wells, The Penguin Dictionary of Curious and Interesting Numbers. Penguin Books, NY, 1986, Revised edition 1987. See p. 90.

Crossrefs

Apart from initial term, same as A045326.
Cf. A016105.
Cf. A004614 (multiplicative closure).

Programs

  • Haskell
    a002145 n = a002145_list !! (n-1)
    a002145_list = filter ((== 1) . a010051) [3, 7 ..]
    -- Reinhard Zumkeller, Aug 02 2015, Sep 23 2011
    
  • Magma
    [4*n+3 : n in [0..142] | IsPrime(4*n+3)]; // Arkadiusz Wesolowski, Nov 15 2013
    
  • Maple
    A002145 := proc(n)
        option remember;
        if n = 1 then
            3;
        else
            a := nextprime(procname(n-1)) ;
            while a mod 4 <>  3 do
                a := nextprime(a) ;
            end do;
            return a;
        end if;
    end proc:
    seq(A002145(n),n=1..20) ; # R. J. Mathar, Dec 08 2011
  • Mathematica
    Select[4Range[150] - 1, PrimeQ] (* Alonso del Arte, Dec 19 2013 *)
    Select[ Prime@ Range[2, 110], Length@ PowersRepresentations[#^2, 2, 2] == 1 &] (* or *)
    Select[ Prime@ Range[2, 110], JacobiSymbol[-1, #] == -1 &] (* Robert G. Wilson v, May 11 2014 *)
  • PARI
    forprime(p=2,1e3,if(p%4==3,print1(p", "))) \\ Charles R Greathouse IV, Jun 10 2011
    
  • Sage
    def A002145_list(n): return [p for p in prime_range(1, n + 1) if p % 4 == 3]  # Peter Luschny, Jul 29 2014

Formula

Remove from A000040 terms that are in A002313.
Intersection of A000040 and A004767. - Alonso del Arte, Apr 22 2014
From Vaclav Kotesovec, Apr 30 2020: (Start)
Product_{k>=1} (1 - 1/a(k)^2) = A243379.
Product_{k>=1} (1 + 1/a(k)^2) = A243381.
Product_{k>=1} (1 - 1/a(k)^3) = A334427.
Product_{k>=1} (1 + 1/a(k)^3) = A334426.
Product_{k>=1} (1 - 1/a(k)^4) = A334448.
Product_{k>=1} (1 + 1/a(k)^4) = A334447.
Product_{k>=1} (1 - 1/a(k)^5) = A334452.
Product_{k>=1} (1 + 1/a(k)^5) = A334451. (End)
From Vaclav Kotesovec, May 05 2020: (Start)
Product_{k>=1} (1 + 1/a(k)) / (1 + 1/A002144(k)) = Pi/(4*A064533^2) = 1.3447728438248695625516649942427635670667319092323632111110962...
Product_{k>=1} (1 - 1/a(k)) / (1 - 1/A002144(k)) = Pi/(8*A064533^2) = 0.6723864219124347812758324971213817835333659546161816055555481... (End)
Sum_{k >= 1} 1/a(k)^s = (1/2) * Sum_{n >= 1 odd numbers} moebius(n) * log(2 * (2^(n*s) - 1) * (n*s - 1)! * zeta(n*s) / (Pi^(n*s) * abs(EulerE(n*s - 1))))/n, s >= 3 odd number. - Dimitris Valianatos, May 20 2020

Extensions

More terms from James Sellers, Apr 21 2000

A079458 Number of Gaussian integers in a reduced system modulo n.

Original entry on oeis.org

1, 2, 8, 8, 16, 16, 48, 32, 72, 32, 120, 64, 144, 96, 128, 128, 256, 144, 360, 128, 384, 240, 528, 256, 400, 288, 648, 384, 784, 256, 960, 512, 960, 512, 768, 576, 1296, 720, 1152, 512, 1600, 768, 1848, 960, 1152, 1056, 2208, 1024, 2352, 800, 2048, 1152, 2704
Offset: 1

Views

Author

Vladeta Jovovic, Jan 14 2003

Keywords

Comments

Number of units in the ring consisting of the Gaussian integers modulo n. - Jason Kimberley, Dec 07 2015

Examples

			{1, i, 1+2i, 2+i, 3, 3i, 3+2i, 2+3i} is the set of eight units in the Gaussian integers modulo 4. - _Jason Kimberley_, Dec 07 2015
		

Crossrefs

Equals four times A218147. - Jason Kimberley, Nov 14 2015
Sequences giving the number of solutions to the equation GCD(x_1^2+...+x_k^2, n) = 1 with 0 < x_i <= n: A000010 (k=1), A079458 (k=2), A053191 (k=3), A227499 (k=4), A238533 (k=5), A238534 (k=6), A239442 (k=7), A239441 (k=8), A239443 (k=9).
Equivalent of arithmetic functions in the ring of Gaussian integers (the corresponding functions in the ring of integers are in the parentheses): A062327 ("d", A000005), A317797 ("sigma", A000203), this sequence ("phi", A000010), A227334 ("psi", A002322), A086275 ("omega", A001221), A078458 ("Omega", A001222), A318608 ("mu", A008683).
Equivalent in the ring of Eisenstein integers: A319445.

Programs

  • Magma
    A079458 := func)>; // Jason Kimberley, Nov 14 2015
    
  • Maple
    with(GaussInt): seq(GIphi(n), n=1..100);
  • Mathematica
    phi[1]=1;phi[p_, s_] := Which[Mod[p, 4] == 3, p^(2 s - 2) (p^2 - 1), Mod[p, 4] == 1, p^(2 s - 2) ((p - 1))^2, True, 2^(2 s - 1)];phi[n_] := Product[phi[FactorInteger[n][[i, 1]], FactorInteger[n][[i, 2]]], {i, Length[FactorInteger[n]]}];Table[phi[n], {n, 1, 33}] (* José María Grau Ribas, Mar 16 2014 *)
    f[p_, e_] := (p - 1)*p^(2*e - 1) * If[p == 2, 1, 1 - (-1)^((p-1)/2)/p]; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, Feb 13 2024 *)
  • PARI
    a(n)=
    {
        my(r=1, f=factor(n));
        for(j=1, #f[, 1], my(p=f[j, 1], e=f[j, 2]);
            if(p==2, r*=2^(2*e-1));
            if(p%4==1, r*=(p-1)^2*p^(2*e-2));
            if(p%4==3, r*=(p^2-1)*p^(2*e-2));
        );
        return(r);
    } \\ Jianing Song, Sep 16 2018

Formula

Multiplicative with a(2^e) = 2^(2*e-1), a(p^e) = (p^2-1)*p^(2*e-2) if p mod 4=3 and a(p^e) = (p-1)^2*p^(2*e-2) if p mod 4=1.
a(n) = A003557(n)^2 * a(A007947(n)), where a(2)=2, a(p)=(p-1)^2 for prime p=1(mod 4), a(p)=p^2-1 for prime p=3(mod 4), and a(n*m)=a(n)*a(m) for n coprime to m. - Jason Kimberley, Nov 16 2015
From Amiram Eldar, Feb 13 2024: (Start)
Dirichlet g.f.: zeta(s-2) * (1 - 1/2^(s-1)) * Product_{p prime > 2} (1 - 1/p^(s-1) - (-1)^((p-1)/2)*(p-1)/p^s).
Sum_{k=1..n} a(k) = c * n^3 / 3 + O(n^2 * log(n)), where c = (3/4) * Product_{p prime > 2} (1 - 1/p^2 - (-1)^((p-1)/2)*(p-1)/p^3) = (3/4) * A334427 * Product_{p prime == 1 (mod 4)} (1 - 2/p^2 + 1/p^3) = 0.6498027559... (Calderón et al., 2015). (End)
a(n) = A204617(n)*A062570(n). - Ridouane Oudra, Jun 05 2024

A334425 Decimal expansion of Product_{k>=1} (1 - 1/A002144(k)^3).

Original entry on oeis.org

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

Views

Author

Vaclav Kotesovec, Apr 30 2020

Keywords

Examples

			0.991251116234099844239776364609097744339415...
		

References

  • B. C. Berndt, Ramanujan's notebook part IV, Springer-Verlag, 1994, p. 64-65.

Crossrefs

Formula

A334424 / A334425 = 105*zeta(3)/(4*Pi^3).
A334425 * A334427 = 8/(7*zeta(3)).

Extensions

More digits from Vaclav Kotesovec, Jun 27 2020

A334426 Decimal expansion of Product_{k>=1} (1 + 1/A002145(k)^3).

Original entry on oeis.org

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

Views

Author

Vaclav Kotesovec, Apr 30 2020

Keywords

Examples

			1.041158072823444580338360569925615669376071...
		

References

  • B. C. Berndt, Ramanujan's notebook part IV, Springer-Verlag, 1994, p. 64-65.

Crossrefs

Formula

A334426 / A334427 = 28*zeta(3)/Pi^3.
A334424 * A334426 = 840*zeta(3)/Pi^6.

Extensions

More digits from Vaclav Kotesovec, Jun 27 2020

A334448 Decimal expansion of Product_{k>=1} (1 - 1/A002145(k)^4).

Original entry on oeis.org

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

Views

Author

Vaclav Kotesovec, Apr 30 2020

Keywords

Comments

In general, for s>1, Product_{k>=1} (1 + 1/A002145(k)^s)/(1 - 1/A002145(k)^s) = 2^s * (2^s - 1) * zeta(s) / (zeta(s, 1/4) - zeta(s, 3/4)).

Examples

			0.98716262542222685648270126457737082772403279729282414743483...
		

References

  • B. C. Berndt, Ramanujan's notebook part IV, Springer-Verlag, 1994, p. 64-65.

Crossrefs

Formula

A334447 / A334448 = 1/(PolyGamma(3, 1/4)/(8*Pi^4) - 1).
A334446 * A334448 = 96/Pi^4.

Extensions

More digits from Vaclav Kotesovec, Jun 27 2020

A155918 Number of squared hypotenuses mod n in two dimensions.

Original entry on oeis.org

1, 2, 3, 3, 5, 6, 7, 5, 7, 10, 11, 9, 13, 14, 15, 9, 17, 14, 19, 15, 21, 22, 23, 15, 25, 26, 21, 21, 29, 30, 31, 17, 33, 34, 35, 21, 37, 38, 39, 25, 41, 42, 43, 33, 35, 46, 47, 27, 43, 50, 51, 39, 53, 42, 55, 35, 57, 58, 59, 45, 61, 62, 49, 33, 65, 66, 67, 51, 69, 70, 71, 35, 73
Offset: 1

Views

Author

Steven Finch, Jan 30 2009

Keywords

Comments

Number of images of the map (x,y) -> x^2+y^2 in Z_n.
Let n = p^e and k = r*p^b (gcd(r,p) = 1). If p == 1 (mod 4), then x^2 + y^2 == k (mod p) always have solutions; if p == 3 (mod 4), then x^2 + y^2 == k (mod p) is solvable if and only if b is even or b >= e; if p = 2, then x^2 + y^2 == k (mod p) is solvable if and only if r == 1 (mod 4) or b >= e - 1. If 0 <= k < n, then the number of solutions to x^2 + y^2 == k (mod n) is A305191(n,k). - Jianing Song, Apr 20 2019

Crossrefs

Programs

  • Mathematica
    (For[v = Table[0, {m, 1, n^2}]; m = 1; i = 0, i < n, i++, For[j = 0, j < n, j++, v[[m]] = Mod[i^2 + j^2, n]; m = m + 1]]; Length[Union[v]])
    (* Second program: *)
    a[n_] := Module[{p, e}, Product[{p, e} = pe; Which[Mod[p, 4] == 1, p^e, Mod[p, 4] == 3, Ceiling[p^(e+1)/(p+1)], p == 2, 2^(e-1) + 1, True, p], {pe, FactorInteger[n]}]];
    Array[a, 100] (* Jean-François Alcover, Jul 30 2020 *)
  • PARI
    a(n) = #Set(vector(n^2, i, ((i%n)^2 + (i\n)^2) % n)); \\ Michel Marcus, Jul 08 2017
    
  • PARI
    a(n)=
    {
        my(r=1, f=factor(n));
        for(j=1, #f[, 1], my(p=f[j, 1], e=f[j, 2]);
            if(p==2, r*=2^(e-1)+1);
            if(p%4==1, r*=p^e);
            if(p%4==3, r*=ceil(p^(e+1)/(p+1)));
        );
        return(r);
    } \\ Jianing Song, Apr 20 2019

Formula

Multiplicative with a(p^e) = p^e if p == 1 (mod 4); ceiling(p^(e+1)/(p+1)) if p == 3 (mod 4); 2^(e-1) + 1 if p = 2. - Jianing Song, Apr 20 2019
Sum_{k=1..n} a(k) ~ c * n^2, where c = (11/24) * Product_{p prime == 3 (mod 4)} (1 - 1/p^3)/(1 - 1/p^4) = (11/24) * A334427/A334448 = 0.44532386516028771931... . - Amiram Eldar, Feb 17 2024

A334452 Decimal expansion of Product_{k>=1} (1 - 1/A002145(k)^5).

Original entry on oeis.org

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

Views

Author

Vaclav Kotesovec, Apr 30 2020

Keywords

Comments

In general, for s>0, Product_{k>=1} (1 + 1/A002145(k)^(2*s+1))/(1 - 1/A002145(k)^(2*s+1)) = (2*s)! * (2^(2*s + 2) - 2) * zeta(2*s+1) / (Pi^(2*s+1) * A000364(s)). - Dimitris Valianatos, May 01 2020
In general, for s>1, Product_{k>=1} (1 + 1/A002145(k)^s)/(1 - 1/A002145(k)^s) = 2^s * (2^s - 1) * zeta(s) / (zeta(s, 1/4) - zeta(s, 3/4)).

Examples

			0.99581872986808059594338516164316597187434727318491056639835771469803963967031...
		

References

  • B. C. Berndt, Ramanujan's notebook part IV, Springer-Verlag, 1994, p. 64-65.

Crossrefs

Formula

A334451 / A334452 = 1488*zeta(5)/(5*Pi^5).
A334450 * A334452 = 32/(31*zeta(5)).

Extensions

More digits from Vaclav Kotesovec, Jun 27 2020

A334478 Decimal expansion of Product_{k>=1} (1 - 1/A002476(k)^3).

Original entry on oeis.org

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

Views

Author

Vaclav Kotesovec, May 02 2020

Keywords

Comments

In general, for s > 0, Product_{k>=1} (1 + 1/A002476(k)^(2*s+1)) / (1 - 1/A002476(k)^(2*s+1)) = sqrt(3) * (2*Pi)^(2*s + 1) * zeta(2*s + 1) * A002114(s) / ((2^(2*s + 1) + 1) * (3^(2*s + 1) + 1) * (2*s)! * zeta(4*s + 2)).
For s > 1, Product_{k>=1} (1 + 1/A002476(k)^s) / (1 - 1/A002476(k)^s) = (zeta(s, 1/6) - zeta(s, 5/6))*zeta(s) / ((2^s + 1)*(3^s + 1)*zeta(2*s)).
For s > 1, Product_{k>=1} (1 - 1/A002476(k)^s) * (1 - 1/A007528(k)^s) = 6^s / ((2^s - 1)*(3^s - 1)*zeta(s)).

Examples

			0.996401692816036632262361122384718799965573818714...
		

Crossrefs

Formula

A334477 / A334478 = 15*sqrt(3)*zeta(3)/Pi^3.
A334478 * A334480 = 108/(91*zeta(3)).

Extensions

More digits from Vaclav Kotesovec, Jun 27 2020

A334480 Decimal expansion of Product_{k>=1} (1 - 1/A007528(k)^3).

Original entry on oeis.org

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

Views

Author

Vaclav Kotesovec, May 02 2020

Keywords

Comments

In general, for s > 0, Product_{k>=1} (1 + 1/A007528(k)^(2*s+1)) / (1 - 1/A007528(k)^(2*s+1)) = (1 - 1/2^(2*s + 1)) * (3^(2*s + 1) - 1) * (2*s)! * zeta(2*s + 1) / (sqrt(3) * A002114(s) * Pi^(2*s + 1)).
For s > 1, Product_{k>=1} (1 + 1/A007528(k)^s) / (1 - 1/A007528(k)^s) = (2^s - 1) * (3^s - 1) * zeta(s) / (zeta(s, 1/6) - zeta(s, 5/6)).
For s > 1, Product_{k>=1} (1 - 1/A002476(k)^s) * (1 - 1/A007528(k)^s) = 6^s / ((2^s - 1)*(3^s - 1)*zeta(s)).

Examples

			0.990884145525213356563403173559432751643483121750... = 1/1.0091997177631243951237...
		

Crossrefs

Formula

A334479 / A334480 = 91*sqrt(3)*zeta(3)/(6*Pi^3).
A334478 * A334480 = 108/(91*zeta(3)).

Extensions

More digits from Vaclav Kotesovec, Jun 27 2020
Showing 1-9 of 9 results.