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.

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A369261 Lexicographically earliest infinite sequence such that a(i) = a(j) => A324644(i) = A324644(j) and A369445(i) = A369445(j), for all i, j >= 1.

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, 15, 23, 16, 20, 24, 25, 26, 27, 21, 28, 29, 30, 29, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 29, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 35, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 62, 53, 51, 70, 71, 72, 58, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 63
Offset: 1

Views

Author

Antti Karttunen, Jan 25 2024

Keywords

Comments

Restricted growth sequence transform of the ordered pair [A324644(n), A369445(n)], or equally, of the pair [A000203(n), A324644(n)], or equally, of the pair [A000203(n), A369445(n)].
For all i, j >= 1: a(i) = a(j) => A286603(i) = A286603(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; };
    A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
    A324644(n) = gcd(sigma(n),A276086(n));
    Aux369261(n) = { my(u=A324644(n)); [u, sigma(n)/u]; };
    v369261 = rgs_transform(vector(up_to, n, Aux369261(n)));
    A369261(n) = v369261[n];

A369446 Denominator of sigma(n) / A276086(n), where A276086 is the primorial base exp-function.

Original entry on oeis.org

2, 1, 3, 9, 3, 5, 5, 1, 30, 5, 15, 25, 25, 25, 25, 225, 25, 125, 25, 125, 375, 125, 375, 125, 1250, 625, 375, 5625, 375, 7, 7, 1, 7, 7, 21, 5, 35, 7, 15, 7, 15, 175, 175, 25, 175, 175, 525, 875, 1750, 875, 875, 1125, 875, 875, 4375, 875, 2625, 875, 2625, 7, 49, 49, 147, 441, 21, 245, 245, 35, 245, 245, 245, 245, 1225
Offset: 1

Views

Author

Antti Karttunen, Jan 25 2024

Keywords

Crossrefs

Cf. A000203, A276086, A324644, A369445 (numerators).

Programs

  • PARI
    A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
    A369446(n) = { my(u=A276086(n)); (u/gcd(u,sigma(n))); };

Formula

a(n) = A276086(n) / A324644(n).
Showing 1-2 of 2 results.