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.

A361020 Lexicographically earliest infinite sequence such that a(i) = a(j) => A343029(i) = A343029(j) and A343030(i) = A343030(j) for all i, j >= 0.

Original entry on oeis.org

1, 2, 3, 4, 2, 5, 6, 7, 3, 4, 5, 8, 4, 9, 10, 11, 2, 5, 6, 7, 5, 8, 9, 12, 6, 7, 8, 13, 7, 14, 15, 16, 3, 4, 5, 8, 4, 9, 10, 11, 5, 8, 9, 12, 8, 13, 14, 17, 4, 9, 10, 11, 9, 12, 13, 18, 10, 11, 12, 19, 11, 20, 21, 22, 2, 5, 6, 7, 5, 8, 9, 12, 6, 7, 8, 13, 7, 14, 15, 16, 5, 8, 9, 12, 8, 13, 14, 17, 9, 12, 13, 18, 12, 19, 20, 23, 6, 7, 8
Offset: 0

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Author

Antti Karttunen, Mar 03 2023

Keywords

Comments

Restricted growth sequence transform of the ordered pair [A343029(n), A343030(n)].
For all i, j >= 0:
a(i) = a(j) => A000120(i) = A000120(j),
a(i) = a(j) => A004718(i) = A004718(j) => A361016(i) = A361016(j).
Because the Danish composer Per Nørgård's "infinity sequence" (A004718) can be represented as an difference A343029(n) - A343030(n), it is a function of this sequence, whose scatter plot shows interesting structure. (The composer Per Nørgård's name is also written in the OEIS as Per Noergaard.)

Crossrefs

Cf. also A286622.

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; };
    A343029(n) = { my(t=1, ret=0); for(i=0, if(n, logint(n, 2)), if(bittest(n, i), ret+=t, t=!t)); ret; }; \\ From A343029
    A343030(n) = { my(t=0, ret=0); for(i=0, if(n, logint(n, 2)), if(bittest(n, i), ret+=t, t=!t)); ret; }; \\ From A343030
    Aux361020(n) = [A343029(n), A343030(n)];
    v361020 = rgs_transform(vector(1+up_to,n,Aux361020(n-1)));
    A361020(n) = v361020[1+n];