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.

A373251 Lexicographically earliest infinite sequence such that a(i) = a(j) => A181819(i) = A181819(j), i mod A181819(i) = j mod A181819(j), and gcd(i,A276086(i)) = gcd(j,A276086(j)), for all i, j >= 1, where A181819 is the prime shadow of n, and A276086 is the primorial base exp-function.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 5, 7, 8, 9, 5, 10, 5, 6, 11, 12, 5, 10, 5, 13, 14, 6, 5, 15, 16, 6, 17, 18, 5, 19, 5, 20, 14, 6, 21, 22, 5, 6, 23, 24, 5, 25, 5, 26, 27, 6, 5, 28, 29, 30, 23, 18, 5, 15, 31, 32, 14, 6, 5, 33, 5, 6, 34, 35, 36, 37, 5, 26, 14, 38, 5, 39, 5, 6, 40, 18, 41, 19, 5, 42, 43, 6, 5, 44, 45, 6, 23, 46, 5, 47, 21, 26, 14, 6
Offset: 1

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Author

Antti Karttunen, May 30 2024

Keywords

Comments

Restricted growth sequence transform of the triple [A181819(n), A373247(n), A324198(n)].
For all i, j:
A305900(i) = A305900(j) => a(i) = a(j),
a(i) = a(j) => A373248(i) = A373248(j),
a(i) = a(j) => A373250(i) = A373250(j).

Crossrefs

Programs

  • PARI
    up_to = 100000;
    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; };
    A181819(n) = factorback(apply(e->prime(e),(factor(n)[,2])));
    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); };
    Aux373251(n) = [A181819(n), n%A181819(n), A324198(n)];
    v373251 = rgs_transform(vector(up_to, n, Aux373251(n)));
    A373251(n) = v373251[n];