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 1-3 of 3 results.

A352868 Expansion of e.g.f. exp(Sum_{k>=1} mu(k) * x^k), where mu() is the Moebius function (A008683).

Original entry on oeis.org

1, 1, -1, -11, -23, -19, 991, 4369, -11311, -356903, 5389471, 7875341, -430708871, -16579950971, 45417621887, 3629980647721, 93982540029601, -1077931879771471, -29167938898699841, -486520057714400603, 7973931691642326281, 205214099791890382621
Offset: 0

Views

Author

Seiichi Manyama, Apr 06 2022

Keywords

Examples

			E.g.f.: A(x) = 1 + x - x^2/2! - 11*x^3/3! - 23*x^4/4! - 19*x^5/5! + 991*x^6/6! + 4369*x^7/7! - 11311*x^8/8! - 356903*x^9/9! + 5389471*x^10/10! + ...
where A(x) = exp(x - x^2 - x^3 - x^5 + x^6 - x^7 + ... + mu(n)*x^n +....);
thus, exp(x) = A(x) * A(x^2) * A(x^3) * ... * A(x^n) * ...
		

Crossrefs

Programs

  • Mathematica
    nmax = 20; A[] = 1; Do[A[x] = Exp[x]/Product[A[x^k], {k, 2, nmax}] + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]*Range[0, nmax]! (* Vaclav Kotesovec, Mar 01 2024 *)
  • PARI
    my(N=40, x='x+O('x^N)); Vec(serlaplace(exp(sum(k=1, N, moebius(k)*x^k))))
    
  • PARI
    a(n) = if(n==0, 1, (n-1)!*sum(k=1, n, k*moebius(k)*a(n-k)/(n-k)!));

Formula

a(0) = 1; a(n) = (n-1)! * Sum_{k=1..n} k * mu(k) * a(n-k)/(n-k)!.
E.g.f. A(x) satisfies Product_{n>=1} A(x^n) = exp(x). - Paul D. Hanna, Feb 29 2024

A352869 Expansion of e.g.f. 1/(1 - Sum_{k>=1} mu(k) * x^k/k!), where mu() is the Moebius function (A008683).

Original entry on oeis.org

1, 1, 1, -1, -14, -71, -201, 559, 14152, 125772, 568873, -2930247, -100950588, -1263405885, -7645798213, 62733063199, 2644646815760, 42203809509047, 312892097907012, -3774840465405301, -184229592151309092, -3541775382376189109, -30473600413019593651
Offset: 0

Views

Author

Seiichi Manyama, Apr 06 2022

Keywords

Crossrefs

Programs

  • PARI
    my(N=40, x='x+O('x^N)); Vec(serlaplace(1/(1-sum(k=1, N, moebius(k)*x^k/k!))))
    
  • PARI
    a(n) = if(n==0, 1, sum(k=1, n, moebius(k)*binomial(n, k)*a(n-k)));

Formula

a(0) = 1; a(n) = Sum_{k=1..n} mu(k) * binomial(n,k) * a(n-k).

A353189 Expansion of e.g.f. exp(Sum_{k>=1} mu(k) * x^k / k), where mu() is the Moebius function (A008683).

Original entry on oeis.org

1, 1, 0, -4, -10, -18, 112, 520, -1188, -21700, 459584, 1186704, -33320120, -917538776, 433679040, 203262002528, 3173401795088, -28004721669360, -854986923602432, -13072356448331840, -17371649304775584, 4477993621700382176, 159817807129635664640
Offset: 0

Views

Author

Seiichi Manyama, Apr 29 2022

Keywords

Crossrefs

Programs

  • Mathematica
    a[0] = 1; a[n_] := a[n] = (n - 1)! * Sum[MoebiusMu[k] * a[n - k]/(n - k)!, {k, 1, n}]; Array[a, 23, 0] (* Amiram Eldar, Apr 30 2022 *)
  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(sum(k=1, N, moebius(k)*x^k/k))))
    
  • PARI
    a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=(i-1)!*sum(j=1, i, moebius(j)*v[i-j+1]/(i-j)!)); v;

Formula

a(0) = 1; a(n) = (n-1)! * Sum_{k=1..n} mu(k) * a(n-k)/(n-k)!.
Showing 1-3 of 3 results.