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 1-3 of 3 results.

A347093 Sum of A322577 (convolution of Dedekind psi with Euler phi) and its Dirichlet inverse.

Original entry on oeis.org

2, 0, 0, 16, 0, 48, 0, 24, 36, 80, 0, 36, 0, 112, 120, 73, 0, 64, 0, 60, 168, 176, 0, 192, 100, 208, 96, 84, 0, 0, 0, 156, 264, 272, 280, 336, 0, 304, 312, 320, 0, 0, 0, 132, 160, 368, 0, 378, 196, 192, 408, 156, 0, 432, 440, 448, 456, 464, 0, 960, 0, 496, 224, 373, 520, 0, 0, 204, 552, 0, 0, 688, 0, 592, 288, 228, 616
Offset: 1

Views

Author

Antti Karttunen, Aug 18 2021

Keywords

Comments

No negative terms in range 1 .. 2^20.
Apparently, A030059 gives the positions of all zeros.

Crossrefs

Programs

  • PARI
    up_to = 16384;
    A001615(n) = if(1==n,n, my(f=factor(n)); prod(i=1, #f~, f[i, 1]^f[i, 2] + f[i, 1]^(f[i, 2]-1))); \\ After code in A001615
    A322577(n) = sumdiv(n,d,A001615(n/d)*eulerphi(d));
    DirInverseCorrect(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = (-u[1]*sumdiv(n, d, if(dA322577(n)));
    A347092(n) = v347092[n];
    A347093(n) = (A322577(n)+A347092(n));

Formula

a(n) = A322577(n) + A347092(n).
For n > 1, a(n) = -Sum_{d|n, 1A322577(d) * A347092(n/d).
For all n >= 1, a(A030059(n)) = 0, a(A030229(n)) = 2*A322577(A030229(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).

A347095 Sum of Pillai's arithmetical function (A018804) and its Dirichlet inverse.

Original entry on oeis.org

2, 0, 0, 9, 0, 30, 0, 21, 25, 54, 0, 35, 0, 78, 90, 49, 0, 51, 0, 63, 130, 126, 0, 95, 81, 150, 85, 91, 0, 0, 0, 113, 210, 198, 234, 172, 0, 222, 250, 171, 0, 0, 0, 147, 153, 270, 0, 235, 169, 147, 330, 175, 0, 231, 378, 247, 370, 342, 0, 405, 0, 366, 221, 257, 450, 0, 0, 231, 450, 0, 0, 424, 0, 438, 245, 259, 546
Offset: 1

Views

Author

Antti Karttunen, Aug 18 2021

Keywords

Comments

No negative terms in range 1 .. 2^20.
Apparently, A030059 gives the positions of all zeros.

Crossrefs

Programs

  • PARI
    up_to = 16384;
    A018804(n) = sumdiv(n, d, n*eulerphi(d)/d); \\ From A018804
    DirInverseCorrect(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = (-u[1]*sumdiv(n, d, if(dA018804(n)));
    A101035(n) = v101035[n];
    A347095(n) = (A018804(n)+A101035(n));

Formula

a(n) = A018804(n) + A101035(n).
For n > 1, a(n) = -Sum_{d|n, 1A018804(d) * A101035(n/d).
For all n >= 1, a(A030059(n)) = 0, a(A030229(n)) = 2*A018804(A030229(n)).
Showing 1-3 of 3 results.