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.

A369067 Lexicographically earliest infinite sequence such that a(i) = a(j) => A369066(i) = A369066(j) for all i, j >= 0.

Original entry on oeis.org

1, 2, 2, 1, 2, 3, 2, 3, 2, 4, 5, 1, 2, 6, 1, 7, 2, 8, 9, 1, 10, 11, 4, 9, 2, 6, 3, 1, 6, 1, 12, 5, 2, 13, 14, 1, 11, 15, 8, 11, 16, 17, 18, 1, 8, 19, 1, 20, 2, 6, 3, 1, 4, 4, 6, 4, 6, 5, 9, 1, 6, 8, 2, 20, 2, 21, 11, 1, 16, 22, 13, 15, 23, 24, 25, 1, 13, 21, 1, 26, 27, 28, 29, 1, 30, 29, 17, 31, 13, 21, 15, 1, 16
Offset: 0

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Author

Antti Karttunen, Jan 16 2024

Keywords

Comments

Restricted growth sequence transform of A369066.

Crossrefs

Cf. also A366805 (compare the scatter plots).

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; };
    A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); (t); };
    A008836(n) = ((-1)^bigomega(n));
    A083345(n) = { my(f=factor(n)); numerator(vecsum(vector(#f~, i, f[i, 2]/f[i, 1]))); };
    A369069(n) = sumdiv(n,d,A008836(n/d)*A083345(d));
    A369066(n) = A369069(A005940(1+n));
    v369067 = rgs_transform(vector(1+up_to,n,A369066(n-1)));
    A369067(n) = v369067[1+n];