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 1-2 of 2 results.

A373268 Lexicographically earliest infinite sequence such that a(i) = a(j) => A003415(i) = A003415(j), A085731(i) = A085731(j) and A373145(i) = A373145(j), for all i, j >= 1.

Original entry on oeis.org

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

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Author

Antti Karttunen, Jun 09 2024

Keywords

Comments

Restricted growth sequence transform of the triple [A003415(n), A085731(n), A373145(n)].
For all i, j >= 1:
A373150(i) = A373150(j) => a(i) = a(j),
a(i) = a(j) => A373151(i) = A373151(j) => A373485(i) = A373485(j),
a(i) = a(j) => A373152(i) = A373152(j),
a(i) = a(j) => A373486(i) = A373486(j).

Crossrefs

Differs from A344025 and A369046 for the first time at n=91, where a(91) = 64, while A344025(91) = A369046(91) = 37.
Differs from A351236 for the first time at n=143, where a(143) = 100, while A351236(143) = 68.

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; };
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A276085(n) = { my(f = factor(n)); sum(k=1, #f~, f[k, 2]*prod(i=1,primepi(f[k, 1]-1),prime(i))); };
    Aux373268(n) = { my(d=A003415(n)); [d, gcd(d,n), gcd(d, A276085(n))]; };
    v373268 = rgs_transform(vector(up_to, n, Aux373268(n)));
    A373268(n) = v373268[n];

A379240 Lexicographically earliest infinite sequence such that a(i) = a(j) => f(i) = f(j), for all i, j, where f(n) = [A003415(n), A085731(n)] if A359550(n) = 1, otherwise f(n) = n.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Dec 19 2024

Keywords

Comments

It is conjectured that this is also the lexicographically earliest infinite sequence such that a(i) = a(j) => A003415(i) = A003415(j), A085731(i) = A085731(j) and A376418(i) = A376418(j), for all i, j >= 1, i.e., the restricted growth sequence transform of the triple [A003415(n), A085731(n), A376418(n)]. This is true if for every pair of i and j for which i <> j, and A376418(i) = A376418(j) > 0, the ordered pairs [A003415(i), A085731(i)] and [A003415(j), A085731(j)] differ from each other.

Crossrefs

Differs from A344025 first at n=140, where a(140) = 97, while A344025(140) = 92.
Differs from A369046 first at n=171, where a(171) = 63, while A369046(171) = 121.

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; };
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A359550(n) = { my(pp); forprime(p=2, , pp = p^p; if(!(n%pp), return(0)); if(pp > n, return(1))); };
    Aux379240(n) = if(!A359550(n), n, my(d=A003415(n)); [d, gcd(d,n)]);
    v379240 = rgs_transform(vector(up_to, n, Aux379240(n)));
    A379240(n) = v379240[n];

Formula

For all i, j >= 1:
a(i) = a(j) => A369051(i) = A369051(j) => A083345(i) = A083345(j),
a(i) = a(j) => A376418(i) = A376418(j).
Showing 1-2 of 2 results.