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.

A366886 Lexicographically earliest infinite sequence such that a(i) = a(j) => A366885(i) = A366885(j) for all i, j >= 0.

Original entry on oeis.org

1, 1, 1, 2, 1, 3, 2, 4, 1, 5, 3, 6, 2, 7, 4, 8, 1, 9, 5, 10, 3, 11, 6, 12, 2, 13, 7, 14, 4, 15, 8, 3, 1, 16, 9, 17, 5, 18, 10, 19, 3, 20, 11, 21, 6, 22, 12, 23, 2, 24, 13, 25, 7, 26, 14, 27, 4, 27, 15, 13, 8, 14, 3, 28, 1, 29, 16, 30, 9, 31, 17, 32, 5, 33, 18, 34, 10, 35, 19, 36, 3, 37, 20, 38, 11, 39, 21, 40, 6
Offset: 0

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Author

Antti Karttunen, Nov 04 2023

Keywords

Comments

Restricted growth sequence transform of A366885.
Albeit quite ugly, the scatter plot is still interesting. - Antti Karttunen, Jan 03 2024

Crossrefs

Cf. also A366806, A366881, A366891 (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; };
    A163511(n) = if(!n, 1, my(p=2, t=1); while(n>1, if(!(n%2), (t*=p), p=nextprime(1+p)); n >>= 1); (t*p));
    A347385(n) = if(1==n,n, my(f=factor(n>>valuation(n, 2))); prod(i=1, #f~, f[i, 1]^f[i, 2] + f[i, 1]^(f[i, 2]-1)));
    A366885(n) = A347385(A163511(n));
    v366886 = rgs_transform(vector(1+up_to,n,A366885(n-1)));
    A366886(n) = v366886[1+n];