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.

A383748 a(n) = q is the smallest integer, such that the numbers -1/q, i/q, -i/q with i = sqrt(-1), are three zeros of the polynomial P(A783747(n),z) = Sum_{k=1..r} d(k)*z^(k-1) where d(1) < d(2), ..., < d(r) are the r divisors of A383747(n).

Original entry on oeis.org

2, 3, 2, 2, 5, 2, 2, 2, 2, 2, 2, 2, 2, 7, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 3, 2, 2, 2, 2, 3, 2, 2, 2, 3, 2, 3, 2, 2, 2, 3, 2, 11, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 3, 3, 2, 2, 3, 2, 2, 2, 2, 3, 2, 3, 2, 2, 2, 2, 3, 2, 2, 3, 13, 2, 3, 2, 2, 2, 2, 3, 2, 2
Offset: 1

Views

Author

Michel Lagneau, May 08 2025

Keywords

Examples

			 n  q  m = A783747(n)         P(m,z)          3 zeros of P(m,z)
 1  2       8          1+2z+4z^2+8z^3         -1/2, -i/2, i/2
 2  3      27          1+3z+9z^2+27z^3        -1/3, -i/3, i/3
 3  2      88          1+2z+4z^2+8z^3+11z^4+  -1/2, -i/2, i/2
                       22z^5+44z^6+88z^7
		

Crossrefs

Programs

  • Maple
    with(numtheory) :
    A:=proc(n) local P, Q, i, q, d, ii:
    d:=divisors(n):P:=add(op(i,d)*x^(i-1),i=1..nops(d)):
    ii:=0:for q from 1 to n while (ii=0) do:
    Q:=(x+1/q)*(x^2+1/q^2):
    if divide(P,Q,'R') then ii:=1:
    A(n):=q:else fi:od:end proc:
    seq(A(n), n=1..2500);