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 1-10 of 13 results. Next

A340198 Dirichlet inverse of sequence f(n) = A319340(n)-1 = (A000010(n) + A023900(n) - 1), where A000010 is Euler Totient function phi, and A023900 is its Dirichlet inverse.

Original entry on oeis.org

1, 1, 1, 1, 1, -1, 1, -1, -2, -5, 1, -8, 1, -9, -13, -9, 1, -16, 1, -22, -21, -17, 1, -28, -14, -21, -20, -36, 1, -43, 1, -31, -37, -29, -45, -49, 1, -33, -45, -62, 1, -67, 1, -64, -64, -41, 1, -69, -34, -64, -61, -78, 1, -68, -77, -96, -69, -53, 1, -88, 1, -57, -96, -79, -93, -115, 1, -106, -85, -123, 1, -95, 1, -69
Offset: 1

Views

Author

Antti Karttunen, Jan 05 2021

Keywords

Comments

Conversely, the Dirichlet inverse of this sequence yields a sequence which is one less than A319340, i.e., pointwise sum s(n) = A109606(n) + A023900(n).
a(9796) = 0 is the only zero among the first 2^22 terms.

Crossrefs

Programs

  • PARI
    A023900(n) = factorback(apply(p -> 1-p, factor(n)[, 1]));
    A319340(n) = (eulerphi(n)+A023900(n));
    A340198(n) = if(1==n,1,-sumdiv(n,d,if(dA319340(n/d)-1)*A340198(d),0)));

Formula

a(1) = 1, for n > 1, a(n) = -Sum_{d|n, dA319340(n/d)-1) * a(d).

A322581 Sum of A003958 and its Dirichlet inverse: a(n) = A003958(n) + A097945(n).

Original entry on oeis.org

2, 0, 0, 1, 0, 4, 0, 1, 4, 8, 0, 2, 0, 12, 16, 1, 0, 4, 0, 4, 24, 20, 0, 2, 16, 24, 8, 6, 0, 0, 0, 1, 40, 32, 48, 4, 0, 36, 48, 4, 0, 0, 0, 10, 16, 44, 0, 2, 36, 16, 64, 12, 0, 8, 80, 6, 72, 56, 0, 8, 0, 60, 24, 1, 96, 0, 0, 16, 88, 0, 0, 4, 0, 72, 32, 18, 120, 0, 0, 4, 16, 80, 0, 12, 128, 84, 112, 10, 0, 16, 144, 22, 120, 92, 144
Offset: 1

Views

Author

Antti Karttunen, Dec 17 2018

Keywords

Crossrefs

Cf. also A319340.

Programs

  • Mathematica
    a[1] = 2; a[n_] := Times @@ ((First[#] - 1)^Last[#] & /@ FactorInteger[n]) + MoebiusMu[n] * EulerPhi[n]; Array[a, 60] (* Amiram Eldar, Dec 17 2018 *)
  • PARI
    A003958(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1]--); factorback(f); };
    A097945(n) = (moebius(n)*eulerphi(n));
    A322581(n) = (A003958(n)+A097945(n));

Formula

a(n) = A003958(n) + A097945(n).

A323364 Sum of Dedekind's psi, A001615, and its Dirichlet inverse, A323363.

Original entry on oeis.org

2, 0, 0, 9, 0, 24, 0, 9, 16, 36, 0, 12, 0, 48, 48, 27, 0, 24, 0, 18, 64, 72, 0, 60, 36, 84, 32, 24, 0, 0, 0, 45, 96, 108, 96, 84, 0, 120, 112, 90, 0, 0, 0, 36, 48, 144, 0, 84, 64, 72, 144, 42, 0, 120, 144, 120, 160, 180, 0, 216, 0, 192, 64, 99, 168, 0, 0, 54, 192, 0, 0, 132, 0, 228, 96, 60, 192, 0, 0, 126, 112, 252, 0, 288, 216, 264, 240, 180, 0
Offset: 1

Views

Author

Antti Karttunen, Jan 13 2019

Keywords

Crossrefs

Programs

A323371 Lexicographically earliest sequence such that for all i, j, a(i) = a(j) => f(i) = f(j) where f(n) = A295886(n) for all other numbers, except f(n) = 0 for odd primes.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Jan 13 2019

Keywords

Comments

Restricted growth sequence transform of function f, defined as f(n) = 0 when n is an odd prime, and f(n) = [A003557(n), A023900(n)] for all other numbers.
For all i, j:
A323370(i) = A323370(j) => a(i) = a(j),
A323405(i) = A323405(j) => a(i) = a(j),
a(i) = a(j) => A092248(i) = A092248(j),
a(i) = a(j) => A319340(i) = A319340(j),
a(i) = a(j) => A322587(i) = A322587(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; };
    A003557(n) = { my(f=factor(n)); for (i=1, #f~, f[i, 2] = max(0,f[i, 2]-1)); factorback(f); };
    A023900(n) = sumdivmult(n, d, d*moebius(d)); \\ From A023900
    Aux323371(n) = if((n>2)&&isprime(n),0,[A003557(n), A023900(n)]);
    v323371 = rgs_transform(vector(up_to, n, Aux323371(n)));
    A323371(n) = v323371[n];

A323370 Lexicographically earliest sequence such that for all i, j, a(i) = a(j) => f(i) = f(j) where f(n) = [A000035(n), A003557(n), A023900(n)] for all other numbers, except f(n) = 0 for odd primes.

Original entry on oeis.org

1, 2, 3, 4, 3, 5, 3, 6, 7, 8, 3, 9, 3, 10, 11, 12, 3, 13, 3, 14, 15, 16, 3, 17, 18, 19, 20, 21, 3, 22, 3, 23, 24, 25, 26, 27, 3, 28, 26, 29, 3, 30, 3, 31, 32, 33, 3, 34, 35, 36, 37, 38, 3, 39, 40, 41, 42, 43, 3, 44, 3, 45, 46, 47, 48, 49, 3, 50, 51, 52, 3, 53, 3, 54, 55, 56, 57, 52, 3, 58, 59, 60, 3, 61, 62, 63, 64, 65, 3, 66, 67, 68, 57, 69, 67, 70, 3, 71, 72, 73, 3, 74, 3, 75, 76
Offset: 1

Views

Author

Antti Karttunen, Jan 13 2019

Keywords

Comments

Restricted growth sequence transform of function f, defined as f(n) = 0 when n is an odd prime, and f(n) = [A000035(n), A003557(n), A023900(n)] for all other numbers.
For all i, j:
A305801(i) = A305801(j) => a(i) = a(j),
a(i) = a(j) => A323367(i) = A323367(j),
a(i) = a(j) => A323371(i) = A323371(j).

Crossrefs

Differs from A323405 for the first time at n=78, where a(78) = 52, while A323405(78) = 58.

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; };
    A003557(n) = { my(f=factor(n)); for (i=1, #f~, f[i, 2] = max(0,f[i, 2]-1)); factorback(f); };
    A023900(n) = sumdivmult(n, d, d*moebius(d)); \\ From A023900
    Aux323370(n) = if((n>2)&&isprime(n),0,[(n%2), A003557(n), A023900(n)]);
    v323370 = rgs_transform(vector(up_to, n, Aux323370(n)));
    A323370(n) = v323370[n];

A323399 Sum of Jordan function J_2(n), A007434 and its Dirichlet inverse, A046970.

Original entry on oeis.org

2, 0, 0, 9, 0, 48, 0, 45, 64, 144, 0, 120, 0, 288, 384, 189, 0, 240, 0, 360, 768, 720, 0, 408, 576, 1008, 640, 720, 0, 0, 0, 765, 1920, 1728, 2304, 888, 0, 2160, 2688, 1224, 0, 0, 0, 1800, 1920, 3168, 0, 1560, 2304, 1872, 4608, 2520, 0, 1968, 5760, 2448, 5760, 5040, 0, 1728, 0, 5760, 3840, 3069, 8064, 0, 0, 4320, 8448, 0, 0, 3480, 0, 8208, 4992, 5400
Offset: 1

Views

Author

Antti Karttunen, Jan 13 2019

Keywords

Crossrefs

Programs

  • PARI
    A007434(n) = sumdiv(n, d, d*d*moebius(n/d));
    A046970(n) = if(1==n,n,my(f=factor(n)); for(i=1, #f~, f[i,1] = 1-(f[i,1]^2)); factorback(f[,1]));
    A323399(n) = (A007434(n) + A046970(n));

Formula

a(n) = A007434(n) + A046970(n).

A319341 a(n) = A000010(n) - A173557(n).

Original entry on oeis.org

0, 0, 0, 1, 0, 0, 0, 3, 4, 0, 0, 2, 0, 0, 0, 7, 0, 4, 0, 4, 0, 0, 0, 6, 16, 0, 16, 6, 0, 0, 0, 15, 0, 0, 0, 10, 0, 0, 0, 12, 0, 0, 0, 10, 16, 0, 0, 14, 36, 16, 0, 12, 0, 16, 0, 18, 0, 0, 0, 8, 0, 0, 24, 31, 0, 0, 0, 16, 0, 0, 0, 22, 0, 0, 32, 18, 0, 0, 0, 28, 52, 0, 0, 12, 0, 0, 0, 30, 0, 16, 0, 22, 0, 0, 0, 30, 0, 36, 40, 36, 0, 0, 0, 36, 0
Offset: 1

Views

Author

Antti Karttunen, Sep 17 2018

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_] := EulerPhi[n] - Times @@ (FactorInteger[n][[;;, 1]] - 1); a[1] = 0; Array[a, 100] (* Amiram Eldar, Dec 21 2023 *)
  • PARI
    A173557(n) = factorback(apply(p -> p-1, factor(n)[, 1]));
    A319341(n) = (eulerphi(n)-A173557(n));

Formula

a(n) = A000010(n) - A173557(n).
a(n) = A318841(n) - A051953(n).
a(A005117(n)) = 0. - Ivan N. Ianakiev, Sep 18 2018
Sum_{k=1..n} a(k) ~ c * n^2 / 2, where c = A059956 - A307868 = 0.136246... . - Amiram Eldar, Dec 21 2023

A323403 Sum of sigma and its Dirichlet inverse: a(n) = A000203(n) + A046692(n).

Original entry on oeis.org

2, 0, 0, 9, 0, 24, 0, 15, 16, 36, 0, 20, 0, 48, 48, 31, 0, 30, 0, 30, 64, 72, 0, 60, 36, 84, 40, 40, 0, 0, 0, 63, 96, 108, 96, 97, 0, 120, 112, 90, 0, 0, 0, 60, 60, 144, 0, 124, 64, 78, 144, 70, 0, 120, 144, 120, 160, 180, 0, 216, 0, 192, 80, 127, 168, 0, 0, 90, 192, 0, 0, 195, 0, 228, 104, 100, 192, 0, 0, 186, 121, 252, 0, 288, 216, 264, 240, 180, 0, 288
Offset: 1

Views

Author

Antti Karttunen, Jan 15 2019

Keywords

Crossrefs

Programs

  • PARI
    up_to = 16384;
    DirInverse(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = -sumdiv(n, d, if(dA047994(n) = { my(f=factor(n)~); prod(i=1, #f, (f[1, i]^f[2, i])-1); };
    v046692 = DirInverse(vector(up_to,n,sigma(n)));
    A046692(n) = v046692[n];
    A323403(n) = (sigma(n)+A046692(n));

Formula

a(n) = A000203(n) + A046692(n).

A323408 Sum of unitary phi and its Dirichlet inverse: a(n) = A047994(n) + A323407(n).

Original entry on oeis.org

2, 0, 0, 1, 0, 4, 0, 5, 4, 8, 0, 10, 0, 12, 16, 15, 0, 12, 0, 20, 24, 20, 0, 18, 16, 24, 24, 30, 0, 0, 0, 35, 40, 32, 48, 32, 0, 36, 48, 36, 0, 0, 0, 50, 48, 44, 0, 30, 36, 32, 64, 60, 0, 28, 80, 54, 72, 56, 0, 8, 0, 60, 72, 71, 96, 0, 0, 80, 88, 0, 0, 64, 0, 72, 64, 90, 120, 0, 0, 60, 88, 80, 0, 12, 128, 84, 112, 90, 0, 16, 144, 110, 120
Offset: 1

Views

Author

Antti Karttunen, Jan 15 2019

Keywords

Crossrefs

Programs

  • PARI
    up_to = 65537;
    DirInverse(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = -sumdiv(n, d, if(dA047994(n) = { my(f=factor(n)~); prod(i=1, #f, (f[1, i]^f[2, i])-1); };
    v323407 = DirInverse(vector(up_to,n,A047994(n)));
    A323407(n) = v323407[n];
    A323408(n) = (A047994(n) + A323407(n));

A323913 Sum of A083254 (2*phi(n) - n) and its Dirichlet inverse.

Original entry on oeis.org

2, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 6, 0, 0, -4, 0, 0, 10, 0, 0, 0, 9, 0, 5, 0, 0, -16, 0, 0, 18, 0, 30, -4, 0, 0, 22, 0, 0, -24, 0, 0, 11, 0, 0, 0, 25, -12, 30, 0, 0, -18, 54, 0, 34, 0, 0, -24, 0, 0, 21, 0, 66, -40, 0, 0, 42, -32, 0, 0, 0, 0, 9, 0, 90, -48, 0, 0, 19, 0, 0, -40, 90, 0, 54, 0, 0, -38, 110, 0, 58, 0, 102, 0, 0, -20
Offset: 1

Views

Author

Antti Karttunen, Feb 12 2019

Keywords

Crossrefs

Programs

  • PARI
    up_to = 16384;
    DirInverse(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = -sumdiv(n, d, if(dA083254(n) = (2*eulerphi(n)-n);
    v323912 = DirInverse(vector(up_to,n,A083254(n)));
    A323912(n) = v323912[n];
    A323913(n) = (A083254(n)+A323912(n));
Showing 1-10 of 13 results. Next