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.

A366878 Lexicographically earliest infinite sequence such that a(i) = a(j) => A366875(i) = A366875(j) for all i, j >= 0.

Original entry on oeis.org

1, 2, 3, 4, 3, 1, 5, 6, 3, 2, 2, 2, 3, 7, 8, 9, 3, 10, 1, 11, 3, 12, 1, 9, 3, 10, 13, 14, 3, 15, 12, 16, 3, 6, 17, 18, 3, 19, 20, 21, 3, 1, 9, 22, 3, 23, 12, 24, 3, 25, 17, 26, 3, 27, 28, 29, 3, 10, 30, 23, 3, 31, 32, 11, 3, 11, 8, 33, 3, 34, 35, 36, 3, 11, 37, 38, 3, 39, 40, 41, 3, 5, 2, 42, 3, 43, 44, 45, 3, 1, 46, 47, 3
Offset: 0

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Author

Antti Karttunen, Oct 27 2023

Keywords

Comments

Restricted growth sequence transform of A366875.

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; };
    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));
    A113415(n) = if(n<1, 0, sumdiv(n, d, if(d%2, (d+1)/2)));
    memoA349915 = Map();
    A349915(n) = if(1==n,1,my(v); if(mapisdefined(memoA349915,n,&v), v, v = -sumdiv(n,d,if(dA113415(n/d)*A349915(d),0)); mapput(memoA349915,n,v); (v)));
    A366875(n) = A349915(A163511(n));
    v366878 = rgs_transform(vector(1+up_to,n,A366875(n-1)));
    A366878(n) = v366878[1+n];

A366873 a(n) = A113415(A163511(n)), where A113415(n) is the average of number of and sum of odd divisors of n.

Original entry on oeis.org

1, 1, 1, 3, 1, 8, 3, 4, 1, 22, 8, 17, 3, 14, 4, 5, 1, 63, 22, 80, 8, 65, 17, 30, 3, 42, 14, 26, 4, 18, 5, 7, 1, 185, 63, 393, 22, 316, 80, 202, 8, 206, 65, 174, 17, 117, 30, 68, 3, 124, 42, 127, 14, 100, 26, 50, 4, 55, 18, 38, 5, 26, 7, 8, 1, 550, 185, 1956, 63, 1567, 393, 1403, 22, 1020, 316, 1204, 80, 804, 202
Offset: 0

Views

Author

Antti Karttunen, Oct 27 2023

Keywords

Crossrefs

Cf. A113415, A163511, A366874 (rgs-transform).
Cf. also A324186, A366797, A366875.

Programs

  • PARI
    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));

Formula

a(n) = (1/2) * (A324186(n)+A366797(n)).

A366879 a(n) = A326938(A163511(n)), where A326938 is the Dirichlet inverse of the sum of divisors d of n such that n/d is odd.

Original entry on oeis.org

1, -2, 0, -4, 0, 3, 8, -6, 0, 0, -6, 5, 0, 24, 12, -8, 0, 0, 0, 0, 0, -20, -10, 7, 0, -18, -48, 48, 0, 32, 16, -12, 0, 0, 0, 0, 0, 0, 0, 0, 0, 15, 40, -42, 0, -28, -14, 11, 0, 0, 36, -40, 0, -192, -96, 96, 0, -24, -64, 72, 0, 48, 24, -14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -30, 35, 0, 168, 84
Offset: 0

Views

Author

Antti Karttunen, Oct 27 2023

Keywords

Crossrefs

Cf. A002131, A163511, A326938, A366880 (rgs-transform).
Cf. also A366875.

Programs

  • PARI
    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));
    A326938(n) = sumdiv(n, d, if(n/d%2, moebius(n/d)*moebius(d)*d));
    A366879(n) = A326938(A163511(n));
Showing 1-3 of 3 results.