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 1-5 of 5 results.

A351346 Dirichlet g.f.: Product_{p prime} 1 / (1 - 2*p^(-s) - p^(-2*s)).

Original entry on oeis.org

1, 2, 2, 5, 2, 4, 2, 12, 5, 4, 2, 10, 2, 4, 4, 29, 2, 10, 2, 10, 4, 4, 2, 24, 5, 4, 12, 10, 2, 8, 2, 70, 4, 4, 4, 25, 2, 4, 4, 24, 2, 8, 2, 10, 10, 4, 2, 58, 5, 10, 4, 10, 2, 24, 4, 24, 4, 4, 2, 20, 2, 4, 10, 169, 4, 8, 2, 10, 4, 8, 2, 60, 2, 4, 10, 10, 4, 8, 2, 58, 29, 4, 2, 20, 4, 4, 4, 24, 2, 20
Offset: 1

Views

Author

Ilya Gutkovskiy, Feb 08 2022

Keywords

Crossrefs

Programs

  • Mathematica
    f[p_, e_] := Fibonacci[e + 1, 2]; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Table[a[n], {n, 1, 90}]
  • PARI
    for(n=1, 100, print1(direuler(p=2, n, 1/(1 - 2*X - X^2))[n], ", ")) \\ Vaclav Kotesovec, Feb 10 2022

Formula

Multiplicative with a(p^e) = Pell(e+1).
From Vaclav Kotesovec, Feb 11 2022: (Start)
Sum_{k=1..n} a(k) ~ c * n^s, where
s = log(1 + sqrt(2)) / log(2) = 1.271553303163611972...,
c = 8.3717222015175571... = (1 + sqrt(2)) / (2^(3/2) * log(1 + sqrt(2))) * Product_{p primes > 2} 1 / (1 - 2*p^(-s) - p^(-2*s)),
or with better convergence
c = zeta(s)^2 / (sqrt(2) * (1 + sqrt(2)) * log(1 + sqrt(2))) * Product_{p primes > 2} (1 - p^(-s))^2 / (1 - 2*p^(-s) - p^(-2*s)). (End)

A351348 Dirichlet g.f.: Product_{p prime} (1 + 2*p^(-s)) / (1 - p^(-s) - p^(-2*s)).

Original entry on oeis.org

1, 3, 3, 4, 3, 9, 3, 7, 4, 9, 3, 12, 3, 9, 9, 11, 3, 12, 3, 12, 9, 9, 3, 21, 4, 9, 7, 12, 3, 27, 3, 18, 9, 9, 9, 16, 3, 9, 9, 21, 3, 27, 3, 12, 12, 9, 3, 33, 4, 12, 9, 12, 3, 21, 9, 21, 9, 9, 3, 36, 3, 9, 12, 29, 9, 27, 3, 12, 9, 27, 3, 28, 3, 9, 12, 12, 9, 27, 3, 33, 11, 9, 3, 36, 9, 9, 9
Offset: 1

Views

Author

Ilya Gutkovskiy, Feb 08 2022

Keywords

Crossrefs

Programs

  • Mathematica
    f[p_, e_] := LucasL[e + 1]; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Table[a[n], {n, 1, 87}]
  • PARI
    for(n=1, 100, print1(direuler(p=2, n, (1 + 2*X)/(1 - X - X^2))[n], ", ")) \\ Vaclav Kotesovec, Feb 10 2022

Formula

Multiplicative with a(p^e) = Lucas(e+1).
a(n) = Sum_{d|n} A074823(d) * A351219(n/d).
From Vaclav Kotesovec, Feb 12 2022: (Start)
Let f(s) = Product_{p prime} (1 + 1/(p^(2*s) - p^s - 1)) * (1 - 3/p^(2*s) + 2/p^(3*s)), then
Sum_{k=1..n} a(k) ~ n * (f(1)*log(n)^2/2 + ((3*g-1)*f(1) + f'(1))*log(n) + (1 - 3*g + 3*g^2 - 3*sg1)*f(1) + (3*g-1)*f'(1) + f''(1)/2), where
f(1) = Product_{prime p} (p-1)^3 * (p+2) / (p^2 (p^2 - p - 1)) = 0.76679494740111861346654669603448358442373234633770198438779408968851774...,
f'(1) = f(1) * Sum_{p prime} (4*p^2 - 9*p - 4) * log(p) / (p^4 - 4*p^2 + p + 2) = -0.2518173642312369311596467494348076414732211832249275289370643712012051...,
f''(1) = f'(1)^2/f(1) + f(1) * Sum_{p prime} -p*(8*p^5 - 27*p^4 - 16*p^3 + 32*p^2 + 16*p + 14) * log(p)^2 / (p^4 - 4*p^2 + p + 2)^2 = 4.28643633804365513728313780779157573071314496047204449783182235740130206...,
gamma is the Euler-Mascheroni constant A001620 and sg1 is the first Stieltjes constant (see A082633). (End)

A347195 Decimal expansion of Sum_{primes p > 2} log(p) / ((p-2)*(p-1)).

Original entry on oeis.org

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

Views

Author

Vaclav Kotesovec, Aug 22 2021

Keywords

Comments

Constant is related to the asymptotics of A069205.

Examples

			0.8593922313585686897187145141861232817699609176983112114741634265903839649...
		

Crossrefs

Programs

  • Mathematica
    ratfun = 1/((p-2)*(p-1)); zetas = 0; ratab = Table[konfun = Simplify[ratfun + c/(p^power - 1)] // Together; coefs = CoefficientList[Numerator[konfun], p]; sol = Solve[Last[coefs] == 0, c][[1]]; zetas = zetas + c*(Zeta'[power]/Zeta[power] + Log[2]/(2^power - 1)) /. sol; ratfun = konfun /. sol, {power, 2, 25}]; Do[Print[N[Sum[Log[p]*ratfun /. p -> Prime[k], {k, 2, m}] + zetas, 110]], {m, 2000, 10000, 2000}]

A351655 Dirichlet g.f.: Product_{p prime} 1 / (1 - p^(-s) - p^(-2*s) - p^(-3*s)).

Original entry on oeis.org

1, 1, 1, 2, 1, 1, 1, 4, 2, 1, 1, 2, 1, 1, 1, 7, 1, 2, 1, 2, 1, 1, 1, 4, 2, 1, 4, 2, 1, 1, 1, 13, 1, 1, 1, 4, 1, 1, 1, 4, 1, 1, 1, 2, 2, 1, 1, 7, 2, 2, 1, 2, 1, 4, 1, 4, 1, 1, 1, 2, 1, 1, 2, 24, 1, 1, 1, 2, 1, 1, 1, 8, 1, 1, 2, 2, 1, 1, 1, 7, 7, 1, 1, 2, 1, 1, 1
Offset: 1

Views

Author

Ilya Gutkovskiy, Feb 16 2022

Keywords

Crossrefs

Programs

  • Mathematica
    t[n_] := t[n] = t[n-1] + t[n-2] + t[n-3]; t[0] = t[1] = 0; t[2] = 1; f[p_, e_] := t[e+2]; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, Sep 18 2023 *)
  • PARI
    for(n=1, 87, print1(direuler(p=2, n, 1/(1 - X - X^2 - X^3))[n], ", "))

Formula

Multiplicative with a(p^e) = A000073(e+2).

A351656 Dirichlet g.f.: Product_{p prime} 1 / (1 - p^(-s) - p^(-2*s) - p^(-3*s) - p^(-4*s)).

Original entry on oeis.org

1, 1, 1, 2, 1, 1, 1, 4, 2, 1, 1, 2, 1, 1, 1, 8, 1, 2, 1, 2, 1, 1, 1, 4, 2, 1, 4, 2, 1, 1, 1, 15, 1, 1, 1, 4, 1, 1, 1, 4, 1, 1, 1, 2, 2, 1, 1, 8, 2, 2, 1, 2, 1, 4, 1, 4, 1, 1, 1, 2, 1, 1, 2, 29, 1, 1, 1, 2, 1, 1, 1, 8, 1, 1, 2, 2, 1, 1, 1, 8, 8, 1, 1, 2, 1, 1, 1
Offset: 1

Views

Author

Ilya Gutkovskiy, Feb 16 2022

Keywords

Crossrefs

Programs

  • Mathematica
    t[e_] := t[e] = If[e < 5, 2^(e-1), t[e-1] + t[e-2] + t[e-3] + t[e-4]]; a[1] = 1; a[n_] := Times @@ t /@ Last @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, Oct 23 2023 *)
  • PARI
    for(n=1, 87, print1(direuler(p=2, n, 1/(1 - X - X^2 - X^3 - X^4))[n], ", "))

Formula

Multiplicative with a(p^e) = A000078(e+3).
Showing 1-5 of 5 results.