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 1-7 of 7 results.

A323365 Sum of Stern's Diatomic sequence, A002487 and its Dirichlet inverse, A317843.

Original entry on oeis.org

2, 0, 0, 1, 0, 4, 0, 1, 4, 6, 0, 2, 0, 6, 12, 1, 0, 4, 0, 3, 12, 10, 0, 2, 9, 10, 8, 3, 0, -4, 0, 1, 20, 10, 18, 4, 0, 14, 20, 3, 0, 4, 0, 5, 4, 14, 0, 2, 9, 5, 20, 5, 0, 8, 30, 3, 28, 14, 0, 4, 0, 10, 20, 1, 30, -8, 0, 5, 28, 0, 0, 4, 0, 22, -2, 7, 30, 0, 0, 3, 16, 22, 0, 8, 30, 26, 28, 5, 0, 20, 30, 7, 20, 18, 42, 2, 0, 9, 4, 7, 0, 4, 0, 5, 0
Offset: 1

Views

Author

Antti Karttunen, Jan 13 2019

Keywords

Crossrefs

Cf. A002487 (also a quadrisection of this sequence), A317843.

Programs

Formula

a(n) = A002487(n) + A317843(n).
From Antti Karttunen, Dec 08 2021: (Start)
a(1) = 2, and for n > 1, a(n) = -Sum_{d|n, 1A002487(d) * A317843(n/d).
a(4*n) = A002487(n).
(End)

A323882 Sum of A126760 and its Dirichlet inverse.

Original entry on oeis.org

2, 0, 0, 1, 0, 2, 0, 1, 1, 4, 0, 1, 0, 6, 4, 1, 0, 1, 0, 2, 6, 8, 0, 1, 4, 10, 1, 3, 0, 0, 0, 1, 8, 12, 12, 1, 0, 14, 10, 2, 0, 0, 0, 4, 2, 16, 0, 1, 9, 14, 12, 5, 0, 1, 16, 3, 14, 20, 0, 2, 0, 22, 3, 1, 20, 0, 0, 6, 16, 12, 0, 1, 0, 26, 14, 7, 24, 0, 0, 2, 1, 28, 0, 3, 24, 30, 20, 4, 0, 2, 30, 8, 22, 32, 28, 1, 0, 25, 4, 9, 0, 0, 0, 5, 12
Offset: 1

Views

Author

Antti Karttunen, Feb 08 2019

Keywords

Comments

From Antti Karttunen, Aug 18 2021: (Start)
No negative terms in range 1 .. 2^20.
Apparently zeros occur only on (some of the) positions given by A030059, with exceptions for example on n = 70, 105, 110, 130, 154, etc, where a(n) > 0.
(End)

Crossrefs

Programs

  • PARI
    up_to = 20000;
    A126760(n) = {n&&n\=3^valuation(n, 3)<A126760
    DirInverseCorrect(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = (-u[1])*sumdiv(n, d, if(dA126760(n)));
    A323881(n) = v323881[n];
    A323882(n) = (A126760(n)+A323881(n));

Formula

a(n) = A126760(n) + A323881(n).
For n > 1, a(n) = -Sum_{d|n, 1A126760(d) * A323881(n/d). - Antti Karttunen, Aug 18 2021

A323887 Sum of Per Nørgård's "infinity sequence" (A004718) and its Dirichlet inverse (A323886).

Original entry on oeis.org

2, 0, 0, 1, 0, -4, 0, -1, 4, 0, 0, 2, 0, -6, 0, 1, 0, 0, 0, 0, 12, -2, 0, -2, 0, 2, 0, 3, 0, -8, 0, -1, 4, 0, 0, 2, 0, -6, -4, 0, 0, 10, 0, 1, 16, -4, 0, 2, 9, -6, 0, -1, 0, 0, 0, -3, 12, 4, 0, 4, 0, -10, -20, 1, 0, 0, 0, 0, 8, -2, 0, -2, 0, 2, 12, 3, 6, -12, 0, 0, -4, -2, 0, 1, 0, -4, -8, -1, 0, 16, -6, 2, 20, -6, 0, -2, 0, 11, 0, 3, 0, -8, 0, 1, 28
Offset: 1

Views

Author

Antti Karttunen, Feb 08 2019

Keywords

Comments

The composer Per Nørgård's name is also written in the OEIS as Per Noergaard.

Crossrefs

Programs

  • PARI
    up_to = 65537;
    A004718list(up_to) = { my(v=vector(up_to)); v[1]=1; v[2]=-1; for(n=3, up_to, v[n] = if(n%2, 1+v[n>>1], -v[n/2])); (v); }; \\ After code in A004718.
    DirInverse(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = -sumdiv(n, d, if(dA004718list(up_to);
    A004718(n) = v004718[n];
    v323886 = DirInverse(v004718);
    A323886(n) = v323886[n];
    A323887(n) = (A004718(n)+A323886(n));

Formula

a(n) = A004718(n) + A323886(n).

A323896 Sum of binary Gray code A003188 and its Dirichlet inverse, A323895.

Original entry on oeis.org

2, 0, 0, 9, 0, 12, 0, 9, 4, 42, 0, 0, 0, 24, 28, 27, 0, 62, 0, -15, 16, 84, 0, 33, 49, 66, 44, -6, 0, -74, 0, 45, 56, 150, 56, -4, 0, 156, 44, 123, 0, 118, 0, -36, 130, 168, 0, 24, 16, -105, 100, -27, 0, -62, 196, 69, 104, 114, 0, 230, 0, 96, 180, 99, 154, 46, 0, -69, 112, 42, 0, 186, 0, 330, -98, -72, 112, 118, 0, 39, 117, 366, 0, 47
Offset: 1

Views

Author

Antti Karttunen, Feb 08 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(dA003188(n) = bitxor(n, n>>1);
    v323895 = DirInverse(vector(up_to,n,A003188(n)));
    A323895(n) = v323895[n];
    A323896(n) = (A003188(n)+A323895(n));

Formula

a(n) = A003188(n) + A323895(n).

A323884 Sum of A322026 and its Dirichlet inverse.

Original entry on oeis.org

2, 0, 0, 4, 0, 12, 0, 8, 9, 4, 0, 8, 0, 4, 6, 8, 0, 4, 0, 4, 6, 4, 0, 0, 1, 4, 15, 4, 0, -2, 0, 12, 6, 4, 2, 13, 0, 4, 6, 4, 0, -2, 0, 4, 5, 4, 0, 22, 1, 2, 6, 4, 0, 7, 2, 4, 6, 4, 0, 8, 0, 4, 5, 20, 2, -2, 0, 4, 6, 0, 0, 38, 0, 4, 3, 4, 2, -2, 0, 10, 13, 4, 0, 8, 2, 4, 6, 4, 0, 16, 2, 4, 6, 4, 2, 28, 0, 2, 5, 4, 0, -2, 0, 4, 0
Offset: 1

Views

Author

Antti Karttunen, Feb 08 2019

Keywords

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; };
    A007814(n) = valuation(n,2);
    A007949(n) = valuation(n,3);
    v322026 = rgs_transform(vector(up_to, n, [A007814(n), A007949(n)]));
    A322026(n) = v322026[n];
    DirInverse(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = -sumdiv(n, d, if(dA323883(n) = v323883[n];
    A323884(n) = (A322026(n)+A323883(n));

Formula

a(n) = A322026(n) + A323883(n).

A323900 Sum of A287896 and its Dirichlet inverse.

Original entry on oeis.org

2, 0, 0, 4, 0, 8, 0, 4, 4, 12, 0, 4, 0, 12, 12, 5, 0, 8, 0, 6, 12, 20, 0, 8, 9, 20, 8, 6, 0, -8, 0, 6, 20, 20, 18, 12, 0, 28, 20, 12, 0, 8, 0, 10, 4, 28, 0, 10, 9, 10, 20, 10, 0, 16, 30, 12, 28, 28, 0, 20, 0, 20, 20, 7, 30, -16, 0, 10, 28, 0, 0, 16, 0, 44, -2, 14, 30, 0, 0, 15, 16, 44, 0, 28, 30, 52, 28, 20, 0, 40
Offset: 1

Views

Author

Antti Karttunen, Feb 12 2019

Keywords

Crossrefs

Programs

  • PARI
    up_to = 20000;
    DirInverse(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = -sumdiv(n, d, if(dA001511(n) = (1+valuation(n,2));
    A002487(n) = { my(a=1, b=0); while(n>0, if(bitand(n, 1), b+=a, a+=b); n>>=1); (b); }; \\ From A002487
    A287896(n) = (A001511(n)*A002487(n));
    v323899 = DirInverse(vector(up_to,n,A287896(n)));
    A323899(n) = v323899[n];
    A323900(n) = (A287896(n)+A323899(n));

Formula

a(n) = A287896(n) + A323899(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).
Showing 1-7 of 7 results.