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.

A318325 a(n) = Sum_{d|n} [moebius(n/d) > 0]*(sigma(d)-d).

Original entry on oeis.org

0, 1, 1, 3, 1, 6, 1, 7, 4, 8, 1, 17, 1, 10, 9, 15, 1, 22, 1, 23, 11, 14, 1, 39, 6, 16, 13, 29, 1, 45, 1, 31, 15, 20, 13, 61, 1, 22, 17, 53, 1, 57, 1, 41, 34, 26, 1, 83, 8, 44, 21, 47, 1, 70, 17, 67, 23, 32, 1, 125, 1, 34, 42, 63, 19, 81, 1, 59, 27, 77, 1, 139, 1, 40, 50, 65, 19, 93, 1, 113, 40, 44, 1, 159, 23, 46, 33, 95, 1, 163, 21
Offset: 1

Views

Author

Antti Karttunen, Aug 26 2018

Keywords

Crossrefs

Programs

  • PARI
    A318325(n) = sumdiv(n,d,(1==moebius(n/d))*(sigma(d)-d));

Formula

a(n) = Sum_{d|n} [A008683(n/d) == 1]*A001065(d).
a(n) = A051953(n) + A318326(n).
a(n) = A291784(n) - A318441(n).

A318326 a(n) = Sum_{d|n} [moebius(n/d) < 0]*(sigma(d)-d).

Original entry on oeis.org

0, 0, 0, 1, 0, 2, 0, 3, 1, 2, 0, 9, 0, 2, 2, 7, 0, 10, 0, 11, 2, 2, 0, 23, 1, 2, 4, 13, 0, 23, 0, 15, 2, 2, 2, 37, 0, 2, 2, 29, 0, 27, 0, 17, 13, 2, 0, 51, 1, 14, 2, 19, 0, 34, 2, 35, 2, 2, 0, 81, 0, 2, 15, 31, 2, 35, 0, 23, 2, 31, 0, 91, 0, 2, 15, 25, 2, 39, 0, 65, 13, 2, 0, 99, 2, 2, 2, 47, 0, 97, 2, 29, 2, 2, 2, 107, 0, 18, 19, 65, 0, 47
Offset: 1

Views

Author

Antti Karttunen, Aug 26 2018

Keywords

Crossrefs

Programs

  • PARI
    A318326(n) = sumdiv(n,d,(-1==moebius(n/d))*(sigma(d)-d));

Formula

a(n) = Sum_{d|n} [A008683(n/d) == -1]*A001065(d).
a(n) = A318325(n) - A051953(n).
a(n) = A318320(n) - A318442(n).

A318442 a(n) = Sum_{d|n} [moebius(n/d) < 0]*A033879(d).

Original entry on oeis.org

0, 1, 1, 1, 1, 3, 1, 1, 2, 5, 1, 1, 1, 7, 6, 1, 1, 5, 1, 3, 8, 11, 1, -3, 4, 13, 5, 5, 1, 9, 1, 1, 12, 17, 10, -7, 1, 19, 14, -1, 1, 15, 1, 9, 11, 23, 1, -11, 6, 21, 18, 11, 1, 11, 14, 1, 20, 29, 1, -17, 1, 31, 15, 1, 16, 27, 1, 15, 24, 29, 1, -31, 1, 37, 25, 17, 16, 33, 1, -9, 14, 41, 1, -15, 20, 43, 30, 5, 1, -1, 18, 21, 32, 47, 22, -27, 1
Offset: 1

Views

Author

Antti Karttunen, Aug 26 2018

Keywords

Crossrefs

Programs

  • PARI
    A318442(n) = sumdiv(n,d,(-1==moebius(n/d))*(d+d-sigma(d)));

Formula

a(n) = Sum_{d|n} [A008683(n/d) == 1]*A033879(d).
a(n) = A318320(n) - A318326(n).
A083254(n) = A318441(n) - a(n).

A319682 Restricted growth sequence transform of A300832.

Original entry on oeis.org

1, 2, 2, 3, 2, 4, 2, 5, 6, 7, 2, 8, 2, 9, 10, 11, 2, 12, 2, 13, 14, 15, 2, 16, 17, 12, 18, 19, 2, 20, 2, 21, 22, 23, 24, 25, 2, 26, 27, 28, 2, 29, 2, 30, 31, 32, 2, 33, 7, 34, 35, 25, 2, 36, 27, 37, 38, 39, 2, 40, 2, 41, 42, 43, 44, 45, 2, 46, 47, 48, 2, 49, 2, 50, 51, 52, 53, 54, 2, 55, 56, 57, 2, 58, 59, 60, 61, 62, 2, 63, 64, 65, 66, 67, 68, 69, 2, 70, 71, 72, 2, 73, 2, 49
Offset: 1

Views

Author

Antti Karttunen, Sep 29 2018

Keywords

Comments

For all i, j: a(i) = a(j) => A318320(i) = A318320(j).

Crossrefs

Programs

  • PARI
    up_to = 65537;
    rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
    A019565(n) = {my(j,v); factorback(Mat(vector(if(n, #n=vecextract(binary(n), "-1..1")), j, [prime(j), n[j]])~))}; \\ From A019565
    A300832(n) = { my(m=1); fordiv(n,d,if(-1==moebius(n/d), m *= A019565(d))); m; };
    v319682 = rgs_transform(vector(up_to,n,A300832(n)));
    A319682(n) = v319682[n];

A318675 Sum of squarefree divisors of n that have an odd number of prime factors.

Original entry on oeis.org

0, 2, 3, 2, 5, 5, 7, 2, 3, 7, 11, 5, 13, 9, 8, 2, 17, 5, 19, 7, 10, 13, 23, 5, 5, 15, 3, 9, 29, 40, 31, 2, 14, 19, 12, 5, 37, 21, 16, 7, 41, 54, 43, 13, 8, 25, 47, 5, 7, 7, 20, 15, 53, 5, 16, 9, 22, 31, 59, 40, 61, 33, 10, 2, 18, 82, 67, 19, 26, 84, 71, 5, 73, 39, 8, 21, 18, 96, 79, 7, 3, 43, 83, 54, 22, 45, 32, 13, 89, 40, 20, 25, 34, 49, 24, 5
Offset: 1

Views

Author

Antti Karttunen, Sep 04 2018

Keywords

Crossrefs

Programs

  • Mathematica
    Array[DivisorSum[#, # &, MoebiusMu@ # == -1 &] &, 96] (* Michael De Vlieger, Sep 04 2018 *)
  • PARI
    A318675(n) = sumdiv(n,d,(-1==moebius(d))*d);

Formula

For all n >= 1, a(n) <= A318677(n).
a(n) = Sum_{d|n} [A008683(d) < 0]*d.
a(n) = A048250(n) - A318674(n).
a(n) = (A048250(n) - A023900(n))/2. - Amiram Eldar, Jun 06 2025
Showing 1-5 of 5 results.