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.

A366874 Lexicographically earliest infinite sequence such that a(i) = a(j) => A366873(i) = A366873(j) for all i, j >= 0, where A366873 is the average of number of and sum of odd divisors of n as permuted by A163511.

Original entry on oeis.org

1, 1, 1, 2, 1, 3, 2, 4, 1, 5, 3, 6, 2, 7, 4, 8, 1, 9, 5, 10, 3, 11, 6, 12, 2, 13, 7, 14, 4, 15, 8, 16, 1, 17, 9, 18, 5, 19, 10, 20, 3, 21, 11, 22, 6, 23, 12, 24, 2, 25, 13, 26, 7, 27, 14, 28, 4, 29, 15, 30, 8, 14, 16, 3, 1, 31, 17, 32, 9, 33, 18, 34, 5, 35, 19, 36, 10, 37, 20, 38, 3, 39, 21, 40, 11, 41, 22, 42, 6
Offset: 0

Views

Author

Antti Karttunen, Oct 27 2023

Keywords

Comments

Restricted growth sequence transform of A366873.

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; };
    A113415(n) = if(n<1, 0, sumdiv(n, d, if(d%2, (d+1)/2)));
    A163511(n) = if(!n, 1, my(p=2, t=1); while(n>1, if(!(n%2), (t*=p), p=nextprime(1+p)); n >>= 1); (t*p));
    A366873(n) = A113415(A163511(n));
    v366874 = rgs_transform(vector(1+up_to,n,A366873(n-1)));
    A366874(n) = v366874[1+n];

A366797 Number of odd divisors permuted by A163511: a(n) = A001227(A163511(n)).

Original entry on oeis.org

1, 1, 1, 2, 1, 3, 2, 2, 1, 4, 3, 3, 2, 4, 2, 2, 1, 5, 4, 4, 3, 6, 3, 3, 2, 6, 4, 4, 2, 4, 2, 2, 1, 6, 5, 5, 4, 8, 4, 4, 3, 9, 6, 6, 3, 6, 3, 3, 2, 8, 6, 6, 4, 8, 4, 4, 2, 6, 4, 4, 2, 4, 2, 2, 1, 7, 6, 6, 5, 10, 5, 5, 4, 12, 8, 8, 4, 8, 4, 4, 3, 12, 9, 9, 6, 12, 6, 6, 3, 9, 6, 6, 3, 6, 3, 3, 2, 10, 8, 8, 6, 12, 6, 6
Offset: 0

Views

Author

Antti Karttunen, Oct 27 2023

Keywords

Crossrefs

Cf. A001227, A163511, A366798 (rgs-transform).
Cf. also A324186, A366873.

Programs

  • PARI
    A001227(n) = numdiv(n>>valuation(n, 2));
    A163511(n) = if(!n, 1, my(p=2, t=1); while(n>1, if(!(n%2), (t*=p), p=nextprime(1+p)); n >>= 1); (t*p));
    A366797(n) = A001227(A163511(n));

Formula

a(n) = 2*A366873(n) - A324186(n).

A366800 Lexicographically earliest infinite sequence such that a(i) = a(j) => A366799(i) = A366799(j) for all i, j >= 0, where A366799 is the number of divisors d of n that are not of the form 4k+2, as permuted by the Doudna sequence.

Original entry on oeis.org

1, 1, 2, 2, 2, 2, 3, 3, 2, 2, 4, 4, 3, 3, 4, 4, 2, 2, 4, 4, 4, 4, 5, 5, 3, 3, 5, 5, 4, 4, 6, 6, 2, 2, 4, 4, 4, 4, 5, 5, 4, 4, 7, 7, 5, 5, 7, 7, 3, 3, 5, 5, 5, 5, 8, 8, 4, 4, 7, 7, 6, 6, 5, 5, 2, 2, 4, 4, 4, 4, 5, 5, 4, 4, 7, 7, 5, 5, 7, 7, 4, 4, 7, 7, 7, 7, 9, 9, 5, 5, 9, 9, 7, 7, 10, 10, 3, 3, 5, 5, 5, 5, 8, 8
Offset: 0

Views

Author

Antti Karttunen, Oct 27 2023

Keywords

Comments

Restricted growth sequence transform of A366799.

Crossrefs

Cf. also A366798.

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; };
    A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); (t); };
    A320111(n) = sumdiv(n,d,(2!=(d%4)));
    A366799(n) = A320111(A005940(1+n));
    v366800 = rgs_transform(vector(1+up_to,n,A366799(n-1)));
    A366800(n) = v366800[1+n];
Showing 1-3 of 3 results.