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.

Showing 1-4 of 4 results.

A373247 a(n) = n mod A181819(n), where A181819(n) is the prime shadow of n.

Original entry on oeis.org

0, 0, 1, 1, 1, 2, 1, 3, 0, 2, 1, 0, 1, 2, 3, 2, 1, 0, 1, 2, 1, 2, 1, 4, 1, 2, 2, 4, 1, 6, 1, 10, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 1, 2, 3, 2, 1, 6, 1, 2, 3, 4, 1, 4, 3, 6, 1, 2, 1, 0, 1, 2, 3, 12, 1, 2, 1, 2, 1, 6, 1, 12, 1, 2, 3, 4, 1, 6, 1, 10, 4, 2, 1, 0, 1, 2, 3, 8, 1, 6, 3, 2, 1, 2, 3, 8, 1, 2, 3, 1, 1, 6, 1, 4, 1
Offset: 1

Views

Author

Antti Karttunen, May 29 2024

Keywords

Crossrefs

Cf. A325755 (positions of 0's), A353566 (their characteristic function).

Programs

A373250 Lexicographically earliest infinite sequence such that a(i) = a(j) => A181819(i) = A181819(j) and i mod A181819(i) = j mod A181819(j), for all i, j >= 1, where A181819 is the prime shadow of n.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, May 30 2024

Keywords

Comments

Restricted growth sequence transform of the ordered pair [A181819(n), A373247(n)].
For all i, j:
A373251(i) = A373251(j) => a(i) = a(j),
a(i) = a(j) => A101296(i) = A101296(j),
a(i) = a(j) => A373246(i) = A373246(j),
a(i) = a(j) => A373249(i) = A373249(j),
a(i) = a(j) => A353566(i) = A353566(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])));
    Aux373250(n) = [A181819(n), n%A181819(n)];
    v373250 = rgs_transform(vector(up_to, n, Aux373250(n)));
    A373250(n) = v373250[n];

A373249 a(n) = A181819(n) / gcd(n, A181819(n)), where A181819(n) is the prime shadow of n.

Original entry on oeis.org

1, 1, 2, 3, 2, 2, 2, 5, 1, 2, 2, 1, 2, 2, 4, 7, 2, 1, 2, 3, 4, 2, 2, 5, 3, 2, 5, 3, 2, 4, 2, 11, 4, 2, 4, 1, 2, 2, 4, 1, 2, 4, 2, 3, 2, 2, 2, 7, 3, 3, 4, 3, 2, 5, 4, 5, 4, 2, 2, 1, 2, 2, 2, 13, 4, 4, 2, 3, 4, 4, 2, 5, 2, 2, 2, 3, 4, 4, 2, 7, 7, 2, 2, 1, 4, 2, 4, 5, 2, 2, 4, 3, 4, 2, 4, 11, 2, 3, 2, 9, 2, 4, 2, 5, 8
Offset: 1

Views

Author

Antti Karttunen, May 30 2024

Keywords

Crossrefs

Cf. A325755 (positions of 1's), A353566 (their characteristic function).

Programs

  • PARI
    A181819(n) = factorback(apply(e->prime(e),(factor(n)[,2])));
    A373249(n) = { my(s=A181819(n)); s/gcd(n, s); };

Formula

a(n) = A181819(n) / A373246(n) = A181819(n) / gcd(n, A181819(n)).

A373248 Lexicographically earliest infinite sequence such that a(i) = a(j) => gcd(i,A181819(i)) = gcd(j,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, 1, 1, 2, 1, 1, 4, 5, 1, 6, 1, 2, 7, 1, 1, 6, 1, 5, 3, 2, 1, 2, 8, 2, 3, 2, 1, 2, 1, 1, 3, 2, 9, 10, 1, 2, 3, 11, 1, 12, 1, 2, 13, 2, 1, 2, 9, 14, 3, 2, 1, 2, 15, 12, 3, 2, 1, 16, 1, 2, 17, 1, 1, 2, 1, 2, 3, 18, 1, 19, 1, 2, 20, 2, 9, 2, 1, 5, 3, 2, 1, 21, 15, 2, 3, 2, 1, 6, 9, 2, 3, 2, 1, 2, 1, 22, 4, 15
Offset: 1

Views

Author

Antti Karttunen, May 29 2024

Keywords

Comments

Restricted growth sequence transform of the ordered pair [A324198(n), A373246(n)].

Crossrefs

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; };
    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); };
    Aux373248(n) = [gcd(n, A181819(n)), A324198(n)];
    v373248 = rgs_transform(vector(up_to, n, Aux373248(n)));
    A373248(n) = v373248[n];
Showing 1-4 of 4 results.