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.

A251662 Dirichlet convolution of Moebius function mu(n) (A008683) with Ternary numbers A001764.

Original entry on oeis.org

1, 0, 2, 11, 54, 270, 1427, 7740, 43260, 246620, 1430714, 8414356, 50067107, 300829144, 1822766463, 11124747912, 68328754958, 422030501802, 2619631042664, 16332922043614, 102240109896265, 642312449787030, 4048514844039119, 25594403732709300, 162250238001816845, 1031147983109715120
Offset: 1

Views

Author

Paul D. Hanna, Jan 04 2015

Keywords

Examples

			G.f.: A(x) = x + 2*x^3 + 11*x^4 + 54*x^5 + 270*x^6 + 1427*x^7 + 7740*x^8 +...
where Sum_{n>=1} A(x^n*(1-x)^(2*n)) = x - x^2:
x-x^2 = A(x*(1-x)^2) + A(x^2*(1-x)^4) + A(x^3*(1-x)^6) + A(x^4*(1-x)^8) +...
		

Crossrefs

Programs

  • PARI
    /* Dirichlet convolution of mu(n) with Ternary numbers A001764: */
    {a(n) = sumdiv(n, d, moebius(n/d) * binomial(3*(d-1), d-1)/(2*d-1))}
    for(n=1, 30, print1(a(n), ", "))
    
  • PARI
    /* G.f. satisfies: Sum_{n>=1} A(x^n*(1-x)^(2*n)) = x-x^2. */
    {a(n)=local(A=[1, 0]); for(i=1, n, A=concat(A, 0); A[#A]=-Vec(sum(n=1, #A, subst(x*Ser(A), x, (x-2*x^2+x^3 +x*O(x^#A))^n)))[#A]); A[n]}
    for(n=1, 30, print1(a(n), ", "))

Formula

G.f. A(x) satisfies: Sum_{n>=1} A((x - 2*x^2 + x^3)^n) = x - x^2.
a(n) = Sum_{d|n} Moebius(n/d) * binomial(3*(d-1), d-1)/(2*d-1).