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.

A191278 Count of Mosaic numbers that equal n.

Original entry on oeis.org

1, 1, 1, 1, 1, 3, 1, 1, 1, 3, 1, 6, 1, 3, 3, 1, 1, 6, 1, 6, 3, 3, 1, 10, 1, 3, 1, 6, 1, 16, 1, 1, 3, 3, 3, 20, 1, 3, 3, 10, 1, 16, 1, 6, 6, 3, 1, 15, 1, 6, 3, 6, 1, 10, 3, 10, 3, 3, 1, 50, 1, 3, 6, 1, 3, 16, 1, 6, 3, 16, 1, 50, 1, 3, 6, 6, 3, 16, 1, 15, 1, 3, 1, 50, 3, 3, 3, 10, 1, 50
Offset: 1

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Author

R. J. Mathar, May 29 2011

Keywords

Comments

The number of solutions x to A000026(x)=n.

Programs

  • Maple
    A191278 := proc(n)
        local f, beta, a, j ;
        f := ifactors(n)[2] ;
        beta := A073093(n) ;
        a := 1/beta ;
        for j in ifactors(n)[2] do
            a := a*binomial(beta, op(2, j) ) ;
        end do:
        a ;
    end proc:

Formula

Let n=product_j p_j^e(j) be the prime factorization of n and beta=A073093(n). Then a(n)*beta = product_j binomial(beta,e(j)). [Gordon-Robertson in A000026, Theorem 1]