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.

A306666 Positive integers x such that x*(7-5*x+x^2)*(6-4*x+x^2) is a square.

Original entry on oeis.org

1, 2, 3, 7, 21
Offset: 1

Views

Author

Dmitry Ezhov, Mar 04 2019

Keywords

Comments

No other terms below 10^6.
No other terms below 10^10. - Chai Wah Wu, Nov 24 2019

Programs

  • Mathematica
    Select[Range[1000], IntegerQ[Sqrt[#*(7 - 5*# + #^2)*(6 - 4*# + #^2)]] &] (* Vaclav Kotesovec, Mar 10 2019 *)
  • PARI
    isok(x)=issquare(x*(7-5*x+x^2)*(6-4*x+x^2));
    
  • Python
    from sympy.ntheory.primetest import is_square
    A306666_list = [n for n in range(1,10**3) if is_square(n*(n*(n*(n*(n - 9) + 33) - 58) + 42))] # Chai Wah Wu, Nov 24 2019