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.

A080305 Denominator of n^mu(n), where mu is the Moebius function (A008683).

Original entry on oeis.org

1, 2, 3, 1, 5, 1, 7, 1, 1, 1, 11, 1, 13, 1, 1, 1, 17, 1, 19, 1, 1, 1, 23, 1, 1, 1, 1, 1, 29, 30, 31, 1, 1, 1, 1, 1, 37, 1, 1, 1, 41, 42, 43, 1, 1, 1, 47, 1, 1, 1, 1, 1, 53, 1, 1, 1, 1, 1, 59, 1, 61, 1, 1, 1, 1, 66, 67, 1, 1, 70, 71, 1, 73, 1, 1, 1, 1, 78, 79, 1, 1, 1, 83, 1, 1, 1, 1, 1, 89, 1, 1, 1, 1
Offset: 1

Views

Author

Reinhard Zumkeller, Feb 13 2003

Keywords

Crossrefs

Cf. A008683.
Numerator: A080304, A080306, A034386.

Programs

Formula

a(n) = if mu(n)<0 then n else 1, where mu is Moebius mu function (A008683).

A080304 Numerator of n^mu(n), where mu is the Moebius function (A008683).

Original entry on oeis.org

1, 1, 1, 1, 1, 6, 1, 1, 1, 10, 1, 1, 1, 14, 15, 1, 1, 1, 1, 1, 21, 22, 1, 1, 1, 26, 1, 1, 1, 1, 1, 1, 33, 34, 35, 1, 1, 38, 39, 1, 1, 1, 1, 1, 1, 46, 1, 1, 1, 1, 51, 1, 1, 1, 55, 1, 57, 58, 1, 1, 1, 62, 1, 1, 65, 1, 1, 1, 69, 1, 1, 1, 1, 74, 1, 1, 77, 1, 1, 1, 1, 82, 1, 1, 85, 86, 87, 1, 1, 1, 91, 1
Offset: 1

Views

Author

Reinhard Zumkeller, Feb 13 2003

Keywords

Crossrefs

Denominator: A080305. Cf. A080306, A080326, A166142.

Programs

Formula

a(n) = if mu(n)>0 then n else 1.

A080326 Denominator of Sum(k^mu(k): 1<=k<=n), where mu is the Moebius function (A008683).

Original entry on oeis.org

1, 2, 6, 6, 30, 30, 210, 210, 210, 210, 2310, 2310, 30030, 30030, 30030, 30030, 510510, 510510, 9699690, 9699690, 9699690, 9699690, 223092870, 223092870, 223092870, 223092870, 223092870, 223092870, 6469693230, 3234846615
Offset: 1

Views

Author

Dean Hickerson, Feb 15 2003

Keywords

Comments

a(n) is a divisor of A034386(n), the product of the primes <= n. Does a(n) = A034386(n) for infinitely many n?

Crossrefs

Numerators are in A080306. Cf. A080304, A080305, A034386.

Programs

  • Mathematica
    Accumulate[Table[n^MoebiusMu[n],{n,30}]]//Denominator (* Harvey P. Dale, Jul 28 2021 *)
  • PARI
    a(n) = denominator(sum(k = 1, n, k^moebius(k))); \\ Michel Marcus, Aug 29 2013

A130492 a(n) = denominator of Sum_{k=1..n} k^mu(n+1-k), where mu(m) = A008683(m).

Original entry on oeis.org

1, 1, 2, 6, 12, 20, 10, 84, 840, 72, 630, 1320, 2772, 1560, 90090, 42, 240240, 1904, 46410, 95760, 639540, 5040, 9699690, 637560, 14316120, 92400, 176125950, 308880, 20078358300, 475020, 33845175, 7447440, 116925953760, 110880, 501401225325, 2227680, 244906200
Offset: 1

Views

Author

Leroy Quet, May 29 2007

Keywords

Comments

Numerator of Sum_{k=1..n} k^mu(n+1-k) is A130491(n).

Crossrefs

Programs

  • Maple
    A130492 := proc(n) denom(add(k^numtheory[mobius](n+1-k),k=1..n)) ; end: seq(A130492(n),n=1..40) ; # R. J. Mathar, Oct 16 2007
  • Mathematica
    Table[Denominator[Sum[k^MoebiusMu[n+1-k], {k, n}]], {n, 37}] (* James C. McMahon, Feb 09 2025 *)

Extensions

More terms from R. J. Mathar, Oct 16 2007
a(36)-a(37) from James C. McMahon, Feb 09 2025

A130491 a(n) = numerator of Sum_{k=1..n} k^mu(n+1-k), where mu(m) = A008683(m).

Original entry on oeis.org

1, 3, 9, 35, 91, 179, 117, 1181, 14113, 1415, 14839, 35617, 85271, 53251, 3503033, 1879, 12165719, 106753, 2870239, 6436711, 46663061, 402271, 850810423, 60658043, 1473361913, 10236631, 21081760033, 39731443, 2762347887557
Offset: 1

Views

Author

Leroy Quet, May 29 2007

Keywords

Comments

Denominator of Sum_{k=1..n} k^mu(n+1-k) is A130492(n).

Crossrefs

Programs

  • Maple
    A130491 := proc(n) numer(add(k^numtheory[mobius](n+1-k),k=1..n)) ; end: seq(A130491(n),n=1..40) ; # R. J. Mathar, Oct 16 2007
  • Mathematica
    Table[Numerator[Sum[k^MoebiusMu[n+1-k],{k,n}]],{n,29}] (* James C. McMahon, Feb 09 2025 *)
  • PARI
    a(n) = numerator(sum(k=1, n, k^moebius(n+1-k))); \\ Michel Marcus, Feb 09 2025

Extensions

More terms from R. J. Mathar, Oct 16 2007
Showing 1-5 of 5 results.