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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A340188 Sum of A063994 and its Dirichlet inverse, where A063994(x) = Product_{primes p dividing x} gcd(p-1, x-1).

Original entry on oeis.org

2, 0, 0, 1, 0, 4, 0, 1, 4, 8, 0, 0, 0, 12, 16, 1, 0, -4, 0, -2, 24, 20, 0, 1, 16, 24, 0, -4, 0, -28, 0, 1, 40, 32, 48, 5, 0, 36, 48, 1, 0, -48, 0, -8, -16, 44, 0, 1, 36, -32, 64, -10, 0, 8, 80, 5, 72, 56, 0, 24, 0, 60, -32, 1, 96, -88, 0, -14, 88, -116, 0, 0, 0, 72, -48, -16, 120, -108, 0, 1, 4, 80, 0, 48, 128, 84, 112
Offset: 1

Views

Author

Antti Karttunen, Dec 31 2020

Keywords

Crossrefs

Programs

  • PARI
    up_to = 65537;
    A063994(n) = { my(f=factor(n)); prod(i=1, #f~, gcd(f[i, 1]-1, n-1)); };
    DirInverse(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = -sumdiv(n, d, if(dA063994(n)));
    A340187(n) = v340187[n];
    A340188(n) = (A063994(n)+A340187(n));

Formula

a(n) = A063994(n) + A340187(n).
a(n) = A340189(n) - A318828(n).

A354105 Sum of A354102 and its Dirichlet inverse.

Original entry on oeis.org

2, 0, 0, 1, 0, 8, 0, 3, 16, 4, 0, 12, 0, 24, 16, 7, 0, 24, 0, 6, 96, 32, 0, 20, 4, 12, 96, 36, 0, 0, 0, 15, 128, 20, 48, 44, 0, 56, 48, 10, 0, 0, 0, 48, 48, 72, 0, 36, 144, 8, 80, 18, 0, 104, 64, 60, 224, 36, 0, 8, 0, 80, 288, 31, 24, 0, 0, 30, 288, 0, 0, 84, 0, 44, 32, 84, 384, 0, 0, 18, 496, 60, 0, 48, 40, 104, 144
Offset: 1

Views

Author

Antti Karttunen, May 18 2022

Keywords

Crossrefs

Programs

Formula

a(n) = A354102(n) + A354104(n).
a(1) = 2, and for n > 1, a(n) = -Sum_{d|n, 1A354102(d) * A354104(n/d).
a(n) = A319340(A267099(n)).

A346488 Lexicographically earliest infinite sequence such that a(i) = a(j) => f(i) = f(j), for all i, j >= 1, where f(n) = 0 if mu(n) = -1, and f(n) = n for all other numbers (with mu = Möbius mu, A008683).

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, 18, 19, 20, 2, 2, 2, 21, 22, 23, 24, 25, 2, 26, 27, 28, 2, 2, 2, 29, 30, 31, 2, 32, 33, 34, 35, 36, 2, 37, 38, 39, 40, 41, 2, 42, 2, 43, 44, 45, 46, 2, 2, 47, 48, 2, 2, 49, 2, 50, 51, 52, 53, 2, 2, 54, 55, 56, 2, 57, 58, 59, 60, 61, 2, 62, 63, 64, 65, 66, 67, 68, 2, 69, 70, 71
Offset: 1

Views

Author

Antti Karttunen, Aug 20 2021

Keywords

Comments

Restricted growth sequence transform of the sequence f(n) = 0 if mu(n) = -1, and f(n) = n for mu(n) >= 0.
For all i, j:
A305800(i) = A305800(j) => a(i) = a(j) => A305980(i) = A305980(j),
a(i) = a(j) => b(i) = b(j), where b is the pointwise sum of any two multiplicative sequences c and d that are Dirichlet inverses of each other. For example, b can be a sequence like A319340, A323885, or A347094.

Crossrefs

Cf. A008683, A070549, A030059 (positions of 2's).

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; };
    Aux346488(n) = if(moebius(n)<0,0,n);
    v346488 = rgs_transform(vector(up_to, n, Aux346488(n)));
    A346488(n) = v346488[n];
    
  • PARI
    A070549(n) = sum(k=1,n,(-1==moebius(k)));
    A346488(n) = if(1==n,1,if(-1==moebius(n),2,1+n-A070549(n)));

Formula

a(1) = 1, and for n > 1, if A008683(n) = -1, a(n) = 2, otherwise a(n) = 1 + n - A070549(n).
Previous Showing 11-13 of 13 results.