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.

A324654 a(n) = A033879(A276086(n)).

Original entry on oeis.org

1, 1, 2, 0, 5, -3, 4, 2, 6, -12, 12, -54, 19, 7, 26, -72, 47, -309, 94, 32, 126, -372, 222, -1584, 469, 157, 626, -1872, 1097, -7959, 6, 4, 10, -12, 22, -60, 22, -4, 18, -156, 6, -612, 102, -44, 58, -876, -74, -3372, 502, -244, 258, -4476, -474, -17172, 2502, -1244, 1258, -22476, -2474, -86172, 41, 25, 66, -96, 141, -459, 148, -46, 102
Offset: 0

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Author

Antti Karttunen, Mar 10 2019

Keywords

Comments

Interestingly, this kind of sampling of deficiency (A033879; recall that the range of A276086 does not cover the whole N) biases it strongly towards negative values: of the first 2310 terms, 1565 are negative (~ 68%) and of the first 30030 terms, 22507 are negative (~ 75%). Compare also to A323174, which covers whole N.

Crossrefs

Programs

  • PARI
    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; };
    A033879(n) = (2*n-sigma(n));
    A324654(n) = A033879(A276086(n));

Formula

a(n) = A033879(A276086(n)).
a(n) = 2*A276086(n) - A324653(n).