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.

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A050334 Number of ordered factorizations of n into numbers with an odd number of prime divisors (prime factors counted with multiplicity).

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 2, 1, 2, 1, 4, 1, 2, 2, 3, 1, 4, 1, 4, 2, 2, 1, 8, 1, 2, 2, 4, 1, 7, 1, 5, 2, 2, 2, 10, 1, 2, 2, 8, 1, 7, 1, 4, 4, 2, 1, 15, 1, 4, 2, 4, 1, 8, 2, 8, 2, 2, 1, 18, 1, 2, 4, 8, 2, 7, 1, 4, 2, 7, 1, 23, 1, 2, 4, 4, 2, 7, 1, 15, 3, 2, 1, 18, 2, 2, 2, 8, 1, 18, 2, 4, 2, 2, 2, 28, 1, 4, 4
Offset: 1

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Author

Christian G. Bower, Oct 15 1999

Keywords

Comments

a(n) depends only on prime signature of n (cf. A025487). So a(24) = a(375) since 24 = 2^3*3 and 375 = 3*5^3 both have prime signature (3,1).

Examples

			From _R. J. Mathar_, May 25 2017: (Start)
a(p) = 1: factorizations p.
a(p^2) = 1: factorizations p*p.
a(p^3) = 2: factorizations p^3, p*p*p.
a(p^4) = 3: factorizations p^3*p, p*p^3, p*p*p*p.
a(p^5) = 5: factorizations p^5, p^3*p*p, p*p^3*p, p*p*p^3, p*p*p*p*p.
a(p*q) = 2: factorizations p*q, q*p. (End)
		

Crossrefs

Programs

  • Maple
    read(transforms):
    A066829m := proc(n)
            if n = 1 or isA026424(n) then
                    1;
            else
                    0;
            end if;
    end proc:
    [1,seq(-A066829m(n),n=2..10000)] ;
    DIRICHLETi(%) ; # R. J. Mathar, May 25 2017

Formula

Dirichlet g.f.: 1/(1-B(s)) where B(s) is D.g.f. of characteristic function of A026424 (essentially A066829).
a(p^k) = A000045(k).
a(A002110(k)) = A006154(k).
a(n) = A050335(A101296(n)). - R. J. Mathar, May 26 2017
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