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 1-6 of 6 results.

A343978 Number of ordered 6-tuples (a,b,c,d,e,f) with gcd(a,b,c,d,e,f)=1 (1<= {a,b,c,d,e,f} <= n).

Original entry on oeis.org

1, 63, 727, 4031, 15559, 45863, 116855, 257983, 526615, 983583, 1755143, 2935231, 4776055, 7407727, 11256623, 16498719, 23859071, 33434063, 46467719, 62949975, 84644439, 111486599, 146142583, 187854119, 240880239, 303814503, 382049919, 473813703, 586746719
Offset: 1

Views

Author

Karl-Heinz Hofmann, May 06 2021

Keywords

References

  • Joachim von zur Gathen and Jürgen Gerhard, Modern Computer Algebra, Cambridge University Press, Second Edition 2003, pp. 53-54.

Crossrefs

Programs

  • PARI
    a(n)={sum(k=1, n+1, moebius(k)*(n\k)^6)} \\ Andrew Howroyd, May 08 2021
    
  • Python
    from labmath import mobius
    def A343978(n): return sum(mobius(k)*(n//k)**6 for k in range(1, n+1))
    
  • Python
    from functools import lru_cache
    @lru_cache(maxsize=None)
    def A343978(n):
        if n == 0:
            return 0
        c, j, k1 = 1, 2, n//2
        while k1 > 1:
            j2 = n//k1 + 1
            c += (j2-j)*A343978(k1)
            j, k1 = j2, n//j2
        return n*(n**5-1)-c+j # Chai Wah Wu, May 17 2021

Formula

a(n) = Sum_{k=1..n} mu(k)*floor(n/k)^6.
Lim_{n->infinity} a(n)/n^6 = 1/zeta(6) = A343359 = 945/Pi^6.
a(n) = n^6 - Sum_{k=2..n} a(floor(n/k)). - Seiichi Manyama, Sep 13 2024

Extensions

Edited by N. J. A. Sloane, Jun 13 2021

A342586 a(n) is the number of pairs (x,y) with 1 <= x, y <= 10^n and gcd(x,y)=1.

Original entry on oeis.org

1, 63, 6087, 608383, 60794971, 6079301507, 607927104783, 60792712854483, 6079271032731815, 607927102346016827, 60792710185772432731, 6079271018566772422279, 607927101854119608051819, 60792710185405797839054887, 6079271018540289787820715707, 607927101854027018957417670303
Offset: 0

Views

Author

Karl-Heinz Hofmann, Mar 16 2021

Keywords

References

  • Joachim von zur Gathen and Jürgen Gerhard, Modern Computer Algebra, Cambridge University Press, Second Edition 2003, pp. 53-54. (See link below.)

Crossrefs

a(n) = 2*A064018(n) - 1. - Hugo Pfoertner, Mar 16 2021
a(n) = A018805(10^n). - Michel Marcus, Mar 16 2021
Related counts of k-tuples:
triples: A071778, A342935, A342841;
quadruples: A082540, A343527, A343193;
5-tuples: A343282;
6-tuples: A343978, A344038. - N. J. A. Sloane, Jun 13 2021

Programs

  • PARI
    a342586(n)=my(s, m=10^n); forfactored(k=1,m,s+=eulerphi(k)); s*2-1 \\ Bruce Garner, Mar 29 2021
    
  • PARI
    a342586(n)=my(s, m=10^n); forsquarefree(k=1,m,s+=moebius(k)*(m\k[1])^2); s \\ Bruce Garner, Mar 29 2021
  • Python
    import math
    for n in range (0,10):
         counter = 0
         for x in range (1, pow(10,n)+1):
            for y in range(1, pow(10,n)+1):
                if math.gcd(y,x) ==  1:
                    counter += 1
         print(n, counter)
    
  • Python
    from functools import lru_cache
    @lru_cache(maxsize=None)
    def A018805(n):
      if n == 1: return 1
      return n*n - sum(A018805(n//j) for j in range(2, n//2+1)) - (n+1)//2
    print([A018805(10**n) for n in range(8)]) # Michael S. Branicky, Mar 18 2021
    

Formula

Lim_{n->infinity} a(n)/10^(2*n) = 6/Pi^2 = 1/zeta(2).

Extensions

a(10) from Michael S. Branicky, Mar 18 2021
More terms using A064018 from Hugo Pfoertner, Mar 18 2021
Edited by N. J. A. Sloane, Jun 13 2021

A342841 Number of ordered triples (x, y, z) with gcd(x, y, z) = 1 and 1 <= {x, y, z} <= 10^n.

Original entry on oeis.org

1, 841, 832693, 832046137, 831916552903, 831908477106883, 831907430687799769, 831907383078281024371, 831907373418800027750413, 831907372722449100147414487, 831907372589073124899487831735, 831907372581823023465031521920149, 831907372580768386561159867257319711
Offset: 0

Views

Author

Karl-Heinz Hofmann, Mar 24 2021

Keywords

Examples

			For visualization, the set(x, y, z) is inscribed in a cube matrix.
"o" stands for a gcd = 1.
"." stands for a gcd > 1.
.
For n=1, the size of the cube matrix is 10 X 10 X 10:
.
                         / : : : : : : : : : :
                        /                               100 Sum (z = 1)
                z = 7 |/1 2 3 4 5 6 7 8 9 10             |
                    --+---------------------             75 Sum (z = 2)
                   1 /| o o o o o o o o o o    10        |
                   2/ | o o o o o o o o o o    10        91 Sum (z = 3)
                   /                           10        |
           z = 8 |/1 2 3 4 5 6 7 8 9 10        10       75 Sum (z = 4)
               --+---------------------        10      /
              1 /| o o o o o o o o o o    10   10     96 Sum (z = 5)
              2/ | o . o . o . o . o .     5    9    /
              /                           10   10   67 Sum (z = 6)
      z = 9 |/1 2 3 4 5 6 7 8 9 10         5   10  /
          --+---------------------        10   10 /
         1 /| o o o o o o o o o o    10    5   --/
         2/ | o o o o o o o o o o    10   10   99 Sum (z = 7)
         /                            7    5   /
z = 10 |/1 2 3 4 5 6 7 8 9 10        10   10  /
     --+---------------------        10    5 /
     1 | o o o o o o o o o o    10    7   --/
     2 | o . o . o . o . o .     5   10   75 Sum (z = 8)
     3 | o o o o o o o o o o    10   10   /
     4 | o . o . o . o . o .     5    7  /
     5 | o o o o . o o o o .     8   10 /
     6 | o . o . o . o . o .     5   --/
     7 | o o o o o o o o o o    10   91 Sum (z = 9)
     8 | o . o . o . o . o .     5   /
     9 | o o o o o o o o o o    10  /
    10 | o . o . . . o . o .     4 /
                                --/
                                72 Sum (z = 10)
                                /
                               |
                            ------
                              841 Cube Sum (z = 1..10)
		

References

  • Joachim von zur Gathen and Jürgen Gerhard, Modern Computer Algebra, Cambridge University Press, Second Edition 2003, pp. 53-54.

Crossrefs

Cf. A342586 (for 10^n X 10^n), A018805, A002117 (zeta(3)), A071778.
Related counts of k-tuples:
triples: A071778, A342935, A342841;
quadruples: A082540, A343527, A343193;
5-tuples: A343282;
6-tuples: A343978, A344038. - N. J. A. Sloane, Jun 13 2021

Programs

  • Python
    import math
    for n in range (0, 10):
         counter = 0
         for x in range (1, pow(10, n)+1):
            for y in range(1, pow(10, n)+1):
                for z in range(1, pow(10, n)+1):
                    if math.gcd(math.gcd(y, x),z) ==  1:
                        counter += 1
         print(n, counter)

Formula

Lim_{n->infinity} a(n)/10^(3*n) = 1/zeta(3) = 1/Apéry's constant.
a(n) = A071778(10^n).

Extensions

a(5)-a(10) from Hugo Pfoertner, Mar 25 2021
a(11) from Hugo Pfoertner, Mar 26 2021
a(12) from Bruce Garner, Mar 29 2021

A343527 Number of ordered quadruples (w, x, y, z) with gcd(w, x, y, z) = 1 and 1 <= {w, x, y, z} <= 2^n.

Original entry on oeis.org

1, 15, 239, 3823, 60735, 972191, 15517679, 248252879, 3969108895, 63506982943, 1015951568815, 16255093526239, 260068569617727, 4161109496115135, 66577084386669199, 1065232436999055375, 17043668344393625999, 272698739815301095247, 4363176901343767529551, 69810828455823683068415, 1116973047989955380768527
Offset: 0

Views

Author

Karl-Heinz Hofmann, Apr 18 2021

Keywords

Examples

			.
For n=3, the size of the gris is 8 X 8 X 8 X 8:
.
              o------------x(w=8)-------------o
             /|.                            ./ |
            / |.                           ./  |
           /  |.                          ./   |
          /   |.                         ./    |
         /    |.                      z(w=8)   |
        /     |.                      . /      |
       /      |.                     . /       |
      /       |.                   .  /     y(w=8)
     o------------------------------.o         |
    |\        /|¯¯¯¯¯¯x(w=1)¯¯¯¯¯¯/. |         |
    | w      / |                 /.| |         |
    |  \ z(w=1)|                /. | |         |
    |   \  /   |y(w=1)         /.  | |         |
    |    \/-------------------/.   | |         |
    |     |                   |    | |         |        w | sums
    |     |  Cube at w = 1    |    | |         |      ----+-----
    |     |    8 X 8 X 8      | _ _| |---------o        1 |  512
    |     |    contains       |    / |         /        2 |  448
    |     |       512         |   /  |        /         3 |  504
    |     |    completely     |  /   |       /          4 |  448
    |     | reduced fractions | /    |      /           5 |  511
    |     |                   |/     |     /            6 |  441
    |     /------------------- \     |    /             7 |  511
    |    /                      \    |   /              8 |  448
    |   w                        w   |  /             ----+-----
    |  /                          \  | /     sum for a(3) | 3823
    | /                            \ |/
    o -------------------------------o
		

Crossrefs

Programs

  • Python
    from labmath import mobius
    def A343527(n): return sum(mobius(k)*(2**n//k)**4 for k in range(1, 2**n+1))

Formula

Lim_{n->infinity} a(n)/2^(4*n) = 1/zeta(4) = A215267 = 90/Pi^4.
a(n) = A082540(2^n).

Extensions

Edited by N. J. A. Sloane, Jun 13 2021

A343282 Number of ordered 5-tuples (v,w, x, y, z) with gcd(v, w, x, y, z) = 1 and 1 <= {v, w, x, y, z} <= 10^n.

Original entry on oeis.org

1, 96601, 9645718621, 964407482028001, 96438925911789115351, 9643875373658964992585011, 964387358678775616636890654841, 96438734235127451288511508421855851, 9643873406165059293451290072800801506621
Offset: 0

Views

Author

Karl-Heinz Hofmann, Apr 10 2021

Keywords

References

  • Joachim von zur Gathen and Jürgen Gerhard, Modern Computer Algebra, Cambridge University Press, Second Edition 2003, pp. 53-54.

Crossrefs

Related counts of k-tuples:
triples: A071778, A342935, A342841;
quadruples: A082540, A343527, A343193;
5-tuples: A343282;
6-tuples: A343978, A344038. - N. J. A. Sloane, Jun 13 2021

Programs

  • Python
    from labmath import mobius
    def A343282(n): return sum(mobius(k)*(10**n//k)**5 for k in range(1, 10**n+1))

Formula

Lim_{n->infinity} a(n)/10^(5*n) = 1/zeta(5) = A343308.
a(n) = A082544(10^n). - Chai Wah Wu, Apr 11 2021

Extensions

Edited by N. J. A. Sloane, Jun 13 2021

A344038 Number of ordered 6-tuples (a,b,c,d,e,f) with gcd(a,b,c,d,e,f)=1 (1<= {a,b,c,d,e,f} <= 10^n).

Original entry on oeis.org

1, 983583, 983029267047, 982960635742968103, 982953384128772770413831, 982952672223441253533233827367, 982952600027678075050509511271466303, 982952593055042000417993486008754893529583, 982952592342881094406730790044111038427637071855
Offset: 0

Views

Author

Karl-Heinz Hofmann, May 07 2021

Keywords

Crossrefs

Related counts of k-tuples:
triples: A071778, A342935, A342841;
quadruples: A082540, A343527, A343193;
5-tuples: A343282;
6-tuples: A343978, A344038. - N. J. A. Sloane, Jun 13 2021

Programs

  • PARI
    a(n)={sum(k=1, 10^n+1, moebius(k)*(10^n\k)^6)} \\ Andrew Howroyd, May 08 2021
  • Python
    from labmath import mobius
    def A344038(n): return sum(mobius(k)*(10**n//k)**6 for k in range(1, 10**n+1))
    

Formula

Lim_{n->infinity} a(n)/10^(6*n) = 1/zeta(6) = A343359 = 945/Pi^4.
a(n) = A343978(10^n).

Extensions

Edited by N. J. A. Sloane, Jun 13 2021
Showing 1-6 of 6 results.