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 1-3 of 3 results.

A326200 Lexicographically earliest sequence such that a(i) = a(j) => sigma(i)/i = sigma(j)/j for all i, j.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 6, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90
Offset: 1

Views

Author

Antti Karttunen, Jun 13 2019

Keywords

Comments

Restricted growth sequence transform of the abundancy index of n.
For all i, j:
a(i) = a(j) <=> A094759(i) = A094759(j),
a(i) = a(j) => A017665(i) = A017665(j),
a(i) = a(j) => A017666(i) = A017666(j).

Crossrefs

Cf. A000396 (positions of 6's), A005820 (positions of 119's).

Programs

  • PARI
    up_to = 105664; \\ (In the same equivalence class as 78, 364 and 6448).
    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; };
    v326200 = rgs_transform(vector(up_to,n,sigma(n)/n));
    A326200(n) = v326200[n];

A326201 Lexicographically earliest sequence such that for all i, j, a(i) = a(j) => f(i) = f(j), where f(n) = 0 if n > 1 and gcd(n,A000005(n)) = 1, with f(n) = n for all other numbers.

Original entry on oeis.org

1, 2, 3, 3, 3, 4, 3, 5, 6, 7, 3, 8, 3, 9, 3, 3, 3, 10, 3, 11, 3, 12, 3, 13, 3, 14, 3, 15, 3, 16, 3, 17, 3, 18, 3, 19, 3, 20, 3, 21, 3, 22, 3, 23, 24, 25, 3, 26, 3, 27, 3, 28, 3, 29, 3, 30, 3, 31, 3, 32, 3, 33, 34, 3, 3, 35, 3, 36, 3, 37, 3, 38, 3, 39, 40, 41, 3, 42, 3, 43, 3, 44, 3, 45, 3, 46, 3, 47, 3, 48, 3, 49, 3, 50, 3, 51, 3, 52, 53, 3, 3, 54, 3, 55, 3
Offset: 1

Views

Author

Antti Karttunen, Jul 11 2019

Keywords

Comments

For all i, j:
A305801(i) = A305801(j) => a(i) = a(j),
a(i) = a(j) => A009191(i) = A009191(j) => A322980(i) = A322980(j).

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; };
    Aux326201(n) = if((n>1) && (1==gcd(n,numdiv(n))),0,n);
    v326201 = rgs_transform(vector(up_to, n, Aux326201(n)));
    A326201(n) = v326201[n];

A326203 Lexicographically earliest sequence such that for all i, j, a(i) = a(j) => f(i) = f(j), where f(n) = 0 if n > 2 and gcd(n,phi(n)) = 1, with f(n) = n for all other numbers.

Original entry on oeis.org

1, 2, 3, 4, 3, 5, 3, 6, 7, 8, 3, 9, 3, 10, 3, 11, 3, 12, 3, 13, 14, 15, 3, 16, 17, 18, 19, 20, 3, 21, 3, 22, 3, 23, 3, 24, 3, 25, 26, 27, 3, 28, 3, 29, 30, 31, 3, 32, 33, 34, 3, 35, 3, 36, 37, 38, 39, 40, 3, 41, 3, 42, 43, 44, 3, 45, 3, 46, 3, 47, 3, 48, 3, 49, 50, 51, 3, 52, 3, 53, 54, 55, 3, 56, 3, 57, 3, 58, 3, 59, 3, 60, 61, 62, 3, 63, 3, 64, 65, 66, 3, 67, 3
Offset: 1

Views

Author

Antti Karttunen, Jul 11 2019

Keywords

Comments

For all i, j:
A305801(i) = A305801(j) => a(i) = a(j),
a(i) = a(j) => A009195(i) = A009195(j) => A297086(i) = A297086(j),
a(i) = a(j) => A000001(i) = A000001(j) => A297086(i) = A297086(j).

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; };
    Aux326203(n) = if((n>2) && (1==gcd(n,eulerphi(n))),0,n);
    v326203 = rgs_transform(vector(up_to, n, Aux326203(n)));
    A326203(n) = v326203[n];
Showing 1-3 of 3 results.