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.

A327963 If A327928(n) > 0, a(n) = A276086(n), otherwise a(n) = A003415(n).

Original entry on oeis.org

0, 1, 1, 9, 1, 5, 1, 15, 6, 7, 1, 25, 1, 9, 150, 225, 1, 21, 1, 375, 10, 13, 1, 625, 10, 15, 3750, 5625, 1, 31, 1, 21, 14, 19, 126, 35, 1, 21, 210, 315, 1, 41, 1, 525, 39, 25, 1, 875, 14, 45, 5250, 7875, 1, 4375, 8750, 13125, 22, 31, 1, 49, 1, 33, 51, 441, 18, 61, 1, 735, 26, 59, 1, 1225, 1, 39, 55, 11025, 18, 71, 1, 18375, 36750, 43, 1, 30625, 22, 45
Offset: 1

Views

Author

Antti Karttunen, Oct 07 2019

Keywords

Comments

After zero, sequence contains only terms of A048103.

Crossrefs

Programs

  • PARI
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A129251(n) = { my(f = factor(n)); sum(k=1, #f~, (f[k, 2]>=f[k, 1])); };
    A276086(n) = { my(i=0,m=1,pr=1,nextpr); while((n>0),i=i+1; nextpr = prime(i)*pr; if((n%nextpr),m*=(prime(i)^((n%nextpr)/pr));n-=(n%nextpr));pr=nextpr); m; };
    A327963(n) = if(1==n,0,my(u=A003415(n)); if(!A129251(u),u,A276086(n)));

Formula

If A327928(n) > 0 [when n is one of the terms in A327929], then a(n) = A276086(n), otherwise a(n) = A003415(n).
For n > 1, a(n) = A276086(A327964(n)).

A327964 a(1) = 1, and for n > 1, a(n) = A276085(A327963(n)).

Original entry on oeis.org

1, 0, 0, 4, 0, 6, 0, 8, 3, 30, 0, 12, 0, 4, 15, 16, 0, 32, 0, 20, 7, 2310, 0, 24, 7, 8, 27, 28, 0, 6469693230, 0, 32, 31, 510510, 35, 36, 0, 32, 39, 40, 0, 7420738134810, 0, 44, 2312, 12, 0, 48, 31, 10, 51, 52, 0, 54, 55, 56, 211, 6469693230, 0, 60, 0, 212, 30032, 64, 5, 1922760350154212639070, 0, 68, 2311, 32589158477190044730, 0, 72, 0, 2312, 216, 76, 5
Offset: 1

Views

Author

Antti Karttunen, Oct 07 2019

Keywords

Crossrefs

Cf. A327929 (a subsequence of fixed points).

Programs

  • PARI
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A129251(n) = { my(f = factor(n)); sum(k=1, #f~, (f[k, 2]>=f[k, 1])); };
    A276086(n) = { my(i=0,m=1,pr=1,nextpr); while((n>0),i=i+1; nextpr = prime(i)*pr; if((n%nextpr),m*=(prime(i)^((n%nextpr)/pr));n-=(n%nextpr));pr=nextpr); m; };
    A327963(n) = if(1==n,0,my(u=A003415(n)); if(!A129251(u),u,A276086(n)));
    A002110(n) = prod(i=1,n,prime(i));
    A276085(n) = { my(f = factor(n)); sum(k=1, #f~, f[k, 2]*A002110(primepi(f[k, 1])-1)); };
    A327964(n) = if(1==n,n,A276085(A327963(n)));

Formula

a(1) = 1, and for n > 1, a(n) = A276085(A327963(n)).
a(p) = 0 for all primes p.
a(A327929(n)) = A327929(n) for all n. [But note that there are also other fixed points.]

A328315 Lexicographically earliest infinite sequence such that a(i) = a(j) => A328099(i) = A328099(j) for all i, j.

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

Views

Author

Antti Karttunen, Oct 14 2019

Keywords

Comments

Restricted growth sequence transform of A328099, defined as A328099(n) = min(A003415(n), A276086(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; };
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A276086(n) = { my(i=0,m=1,pr=1,nextpr); while((n>0),i=i+1; nextpr = prime(i)*pr; if((n%nextpr),m*=(prime(i)^((n%nextpr)/pr));n-=(n%nextpr));pr=nextpr); m; };
    A328099(n) = min(A003415(n),A276086(n));
    v328315 = rgs_transform(vector(up_to, n, A328099(n)));
    A328315(n) = v328315[n];
Showing 1-3 of 3 results.