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 1-6 of 6 results.

A333239 Decimal expansion of lim_{n->infinity} (Product_{k=1..n} p(k)^2 / Product_{k=1..n} (p(k)^2 - 1)) where p(k) = A167135(k) are the primes with p mod 12 != 1.

Original entry on oeis.org

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

Views

Author

Peter Luschny, May 13 2020

Keywords

Examples

			1.63250540290251307901036625893553760497201130044326292653142032442675746272540...
		

Crossrefs

Formula

A301430 Decimal expansion of an analog of the Landau-Ramanujan constant for Loeschian numbers which are sums of two squares.

Original entry on oeis.org

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

Views

Author

Michel Waldschmidt, Mar 21 2018

Keywords

Comments

This is the decimal expansion of the number alpha such that the number of positive integers <= N which are sums of two squares and are also represented by the quadratic form x^2 + xy + y^2 is asymptotic to alpha*N*(log(N))^(-3/4).
Based on the constants Zeta(m=12,n=5,s=2) = 1.0482019036007..., Zeta(m=12,n=7,s=2) = 1.0262021468... and Zeta(m=12,n=11,s=2) = 1.01177863 ... read from arXiv:1008.2547 we have Product_{p == 5, 7, 11(mod 12)} (1-1/p^2)^(-1/2) = sqrt( Zeta(m=12,n=5,s=2) * Zeta(m=12,n=7,s=2) * Zeta(m=12,n=11,s=2) ) as a factor in the formulas. - R. J. Mathar, Feb 04 2021

Examples

			0.30231614235706563794776990048019971560241279...
		

Crossrefs

Programs

  • Maple
    Digits:= 1000: with(numtheory):
    B:= evalf(3^(1/4)*Pi^(1/2)*log(2+sqrt(3))^(1/4)/(2^(5/4)*GAMMA(1/4))):
    for t to 500 do p:=ithprime(t): if `or`(`or`(`mod`(p, 12) = 5, `mod`(p, 12) = 7), `mod`(p, 12) = 11) then B:= evalf(B/(1-1/p^2)^(1/2)) end if end do: B;
  • Mathematica
    prec := 200; B = N[(Sqrt[Pi] ((3 Log[2 + Sqrt[3]])/2)^(1/4))/(2 Gamma[1/4]), prec];
    For[n = 3, n < 50000, n++, p = Prime[n];
    If[Mod[p, 12] != 1, B = B / Sqrt[(1 - 1/p) (1 + 1/p)]]]
    Print[B] (* Peter Luschny, Mar 23 2018 *)
    (* -------------------------------------------------------------------------- *)
    S[m_, n_, s_] := (t = 1; sums = 0; difs = 1; While[Abs[difs] > 10^(-digits - 5) || difs == 0, difs = (MoebiusMu[t]/t) * Log[If[s*t == 1, DirichletL[m, n, s*t], Sum[Zeta[s*t, j/m]*DirichletCharacter[m, n, j]^t, {j, 1, m}]/m^(s*t)]]; sums = sums + difs; t++]; sums);
    P[m_, n_, s_] := 1/EulerPhi[m] * Sum[Conjugate[DirichletCharacter[m, r, n]] * S[m, r, s], {r, 1, EulerPhi[m]}] + Sum[If[GCD[p, m] > 1 && Mod[p, m] == n, 1/p^s, 0], {p, 1, m}];
    Z[m_, n_, s_] := (w = 1; sumz = 0; difz = 1; While[Abs[difz] > 10^(-digits - 5), difz = P[m, n, s*w]/w; sumz = sumz + difz; w++]; Exp[sumz]);
    $MaxExtraPrecision = 1000; digits = 121; RealDigits[Chop[N[(3^(1/4)/2^(5/4)) * Pi^(1/2) * (Log[2 + Sqrt[3]])^(1/4) / Gamma[1/4] * Sqrt[Z[12, 5, 2] * Z[12, 7, 2] * Z[12, 11, 2]], digits]], 10, digits-1][[1]] (* Vaclav Kotesovec, Jan 15 2021 *)

Formula

Equals (3^(1/4)/2^(5/4)) * Pi^(1/2) * (log(2 + sqrt(3)))^(1/4) / Gamma(1/4) * Product_{p == 5, 7, 11 (mod 12), p prime} (1 - 1/p^2)^(-1/2).
One can base the definition on p(n) = A167135(n). Setting r(n) = (Product_{k=1..n} p(k)^2) / (Product_{k=1..n} (p(k)^2 - 1)) the rational sequence r(n) starts 4/3, 3/2, 25/16, 1225/768, 29645/18432, ... -> L. Then A301430 = sqrt(L)*M with M = ((arccosh(2)/6)^(1/4)*Gamma(3/4))/(2*sqrt(Pi)). - Peter Luschny, Mar 29 2018

Extensions

Offset corrected by Vaclav Kotesovec, Mar 25 2018
a(6)-a(10) from Peter Luschny, Mar 29 2018
More digits from Ettahri article added by Vaclav Kotesovec, May 12 2020
More digits from Vaclav Kotesovec, Jan 15 2021

A167134 Primes congruent to {2, 3, 5, 7} mod 11.

Original entry on oeis.org

2, 3, 5, 7, 13, 29, 47, 71, 73, 79, 101, 113, 137, 139, 157, 167, 179, 181, 211, 223, 227, 233, 269, 271, 277, 293, 311, 313, 337, 359, 379, 401, 409, 421, 431, 443, 467, 487, 491, 509, 541, 557, 563, 577, 599, 601, 607, 619, 641, 643, 673, 709, 733, 739, 751
Offset: 1

Views

Author

Klaus Brockhaus, Oct 28 2009

Keywords

Comments

Primes p such that p mod 11 is prime.
Primes of the form 11*n+r where n >= 0 and r is in {2, 3, 5, 7}.
2 and primes congruent to {3, 5, 7, 13} mod 22. - Chai Wah Wu, Apr 29 2025

Crossrefs

Cf. A003627, A045326, A003631, A045309, A045314, A042987, A078403, A042993, A167134, A167135, A167119: primes p such that p mod k is prime, for k = 3..13 resp.

Programs

  • Magma
    [ p: p in PrimesUpTo(760) | p mod 11 in {2, 3, 5, 7} ];
    [ p: p in PrimesUpTo(760) | exists(t){ n: n in [0..p div 11] | exists(u){ r: r in {2, 3, 5,7} | p eq (11*n+r) } } ];
  • Mathematica
    Select[Prime[Range[600]],MemberQ[{2, 3, 5, 7},Mod[#,11]]&] (* Vincenzo Librandi, Aug 05 2012 *)

A167119 Primes congruent to 2, 3, 5, 7 or 11 (mod 13).

Original entry on oeis.org

2, 3, 5, 7, 11, 29, 31, 37, 41, 59, 67, 83, 89, 107, 109, 137, 163, 167, 193, 197, 211, 223, 239, 241, 263, 271, 293, 317, 349, 353, 367, 379, 397, 401, 419, 421, 431, 449, 457, 479, 499, 509, 523, 557, 577, 587, 601, 613, 631, 653, 661, 683, 691, 709, 733, 739, 743, 757
Offset: 1

Views

Author

Keywords

Comments

Primes which have a remainder mod 13 that is prime.
Union of A141858, A100202, A102732, A140371 and A140373. - R. J. Mathar, Oct 29 2009

Examples

			11 mod 13 = 11, 29 mod 13 = 3, 31 mod 13 = 5, hence 11, 29 and 31 are in the sequence.
		

Crossrefs

Cf. A003627, A045326, A003631, A045309, A045314, A042987, A078403, A042993, A167134, A167135: primes p such that p mod k is prime, for k = 3..12 resp.

Programs

  • Magma
    [ p: p in PrimesUpTo(740) | p mod 13 in {2, 3, 5, 7, 11} ]; // Klaus Brockhaus, Oct 28 2009
  • Mathematica
    f[n_]:=PrimeQ[Mod[n,13]]; lst={};Do[p=Prime[n];If[f[p],AppendTo[lst,p]],{n,6,6!}];lst
    Select[Prime[Range[4000]],MemberQ[{2, 3, 5, 7, 11},Mod[#,13]]&] (* Vincenzo Librandi, Aug 05 2012 *)
  • PARI
    {forprime(p=2, 740, if(isprime(p%13), print1(p, ",")))} \\ Klaus Brockhaus, Oct 28 2009
    

Extensions

Edited by Klaus Brockhaus and R. J. Mathar, Oct 28 2009 and Oct 29 2009

A215161 Primes congruent to {2, 3, 5, 7, 11} mod 17.

Original entry on oeis.org

2, 3, 5, 7, 11, 19, 37, 41, 53, 71, 73, 79, 107, 109, 113, 139, 173, 181, 211, 223, 241, 257, 277, 283, 311, 313, 317, 347, 359, 379, 419, 449, 461, 479, 487, 521, 547, 563, 617, 619, 631, 653, 683, 691, 719, 733, 751, 787, 821, 823, 827, 853, 857, 887, 929
Offset: 1

Views

Author

Vincenzo Librandi, Aug 05 2012

Keywords

Crossrefs

Programs

  • Magma
    [ p: p in PrimesUpTo(1000) | p mod 17 in {2, 3, 5, 7, 11} ];
  • Mathematica
    Select[Prime[Range[400]],MemberQ[{2,3, 5, 7, 11},Mod[#,17]]&]

A215162 Primes congruent to {2, 3, 5, 7, 11} mod 19.

Original entry on oeis.org

2, 3, 5, 7, 11, 41, 43, 59, 79, 83, 97, 157, 163, 173, 193, 197, 211, 233, 239, 269, 271, 277, 307, 311, 347, 349, 353, 383, 401, 421, 439, 461, 463, 467, 499, 577, 613, 619, 653, 691, 727, 733, 743, 809, 839, 857, 877, 881, 919, 953, 971, 991
Offset: 1

Views

Author

Vincenzo Librandi, Aug 05 2012

Keywords

Crossrefs

Programs

  • Magma
    [ p: p in PrimesUpTo(1000) | p mod 19 in {2, 3, 5, 7, 11} ];
  • Mathematica
    Select[Prime[Range[400]],MemberQ[{2,3, 5, 7, 11},Mod[#,19]]&]
Showing 1-6 of 6 results.