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.

A300825 Filter sequence combining A300823(n) and A300824(n).

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Mar 14 2018

Keywords

Comments

Restricted growth sequence transform of ordered pair [A300823(n), A300824(n)].
For all i, j: a(i) = a(j) => A051953(i) = A051953(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; };
    write_to_bfile(start_offset,vec,bfilename) = { for(n=1, length(vec), write(bfilename, (n+start_offset)-1, " ", vec[n])); }
    A244042(n) = fromdigits(apply(x->(x%2), digits(n, 3)), 3);
    A300823(n) = -sumdiv(n,d,(dA244042(d));
    A300222(n) = (n - A244042(n));
    A300824(n) = -sumdiv(n,d,(dA300222(d));
    Aux300825(n) = [A300823(n), A300824(n)];
    write_to_bfile(1,rgs_transform(vector(up_to,n,Aux300825(n))),"b300825.txt");

A300824 Difference between A300222(n) and its Möbius transform.

Original entry on oeis.org

0, 0, 0, 2, 0, 2, 0, 0, 0, 4, 0, 4, 0, 8, 2, 8, 0, 6, 0, -2, 6, 4, 0, 8, 2, 2, 0, 0, 0, 8, 0, 6, 2, 10, 8, 12, 0, 20, 0, 28, 0, 18, 0, 16, 6, 22, 0, 22, 6, 22, 8, 24, 0, 18, 4, 8, 18, 4, 0, 16, 0, 2, 18, 2, 2, 26, 0, 4, 20, 0, 0, 24, 0, 2, 28, 0, 8, 30, 0, -2, 0, 4, 0, 0, 10, 8, 2, 16, 0, 24, 6, 16, 0, 22, 20, 14, 0, 14, 6, 40, 0, 26, 0, 32, 24
Offset: 1

Views

Author

Antti Karttunen, Mar 14 2018

Keywords

Crossrefs

Programs

  • Mathematica
    f[n_] := FromDigits[IntegerDigits[n, 3] /. 1 -> 0, 3]; Table[f@ n - DivisorSum[n, MoebiusMu[n/#] f@ # &], {n, 105}] (* Michael De Vlieger, Mar 17 2018 *)
  • PARI
    A300222(n) = fromdigits(apply(x->(if (1==x, 0, x)), digits(n, 3)), 3);
    A300824(n) = -sumdiv(n,d,(dA300222(d));

Formula

a(n) = A300222(n) - A300822(n).
a(n) = -Sum_{d|n, dA008683(n/d)*A300222(d) = Sum_{d|n, dA300822(d).
a(n) = A051953(n) - A300823(n).

A300821 Möbius transform of A244042.

Original entry on oeis.org

1, -1, 2, 4, 2, -2, 0, -4, 6, 8, 8, 8, 12, 12, 4, 10, 8, -6, 0, -14, 0, -4, 2, -8, -2, -12, 18, 12, 26, 16, 30, 20, 16, 20, 24, 24, 36, 36, 24, 44, 38, 24, 36, 28, 12, 26, 26, 20, 30, 22, 16, 24, 26, -18, -10, -24, 0, -22, 2, -28, 0, -30, 0, -20, -6, -8, 12, -20, 4, -36, 8, -24, 0, -36, -4, -36, -6, -24, 0, -50, 54, 44, 80, 24
Offset: 1

Views

Author

Antti Karttunen, Mar 14 2018

Keywords

Crossrefs

Programs

  • Mathematica
    Table[DivisorSum[n, MoebiusMu[n/#] FromDigits[IntegerDigits[#, 3] /. 2 -> 0, 3] &], {n, 84}] (* Michael De Vlieger, Mar 17 2018 *)
  • PARI
    A244042(n) = fromdigits(apply(x->(x%2), digits(n, 3)), 3);
    A300821(n) = sumdiv(n,d,moebius(n/d)*A244042(d));

Formula

a(n) = Sum_{d|n} moebius(n/d)*A244042(d).
a(n) = A000010(n) - A300822(n).
a(n) = A244042(n) - A300823(n).
Showing 1-3 of 3 results.