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.

A351080 Lexicographically earliest infinite sequence such that a(i) = a(j) => A324198(i) = A324198(j) and A351083(i) = A351083(j) for all i, j >= 0.

Original entry on oeis.org

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

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Author

Antti Karttunen, Feb 03 2022

Keywords

Comments

Restricted growth sequence transform of the ordered pair [A324198(n), A351083(n)].
For all i, j: a(i) = a(j) => A351084(i) = A351084(j).

Crossrefs

Cf. also A351085.

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; };
    A327860(n) = { my(s=0, m=1, p=2, e); while(n, e = (n%p); m *= (p^e); s += (e/p); n = n\p; p = nextprime(1+p)); (s*m); };
    A324198(n) = { my(m=1, p=2, orgn=n); while(n, m *= (p^min(n%p, valuation(orgn, p))); n = n\p; p = nextprime(1+p)); (m); };
    A351083(n) = gcd(n, A327860(n));
    Aux351080(n) = [A324198(n), A351083(n)];
    v351080 = rgs_transform(vector(1+up_to,n,Aux351080(n-1)));
    A351080(n) = v351080[1+n];