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.

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A260373 The nearest perfect square to n!

Original entry on oeis.org

1, 1, 1, 4, 25, 121, 729, 5041, 40401, 362404, 3629025, 39917124, 478996996, 6226945921, 87178467600, 1307674583296, 20922793332736, 355687416544329, 6402373660047556, 121645100663836929, 2432902009335560361, 51090942169052381124, 1124000727752683686724
Offset: 0

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Author

Otis Tweneboah, Pratik Koirala, Eugene Fiorini, Nathan Fox, Jul 23 2015

Keywords

Comments

a(n) is well defined as the squares are alternatingly odd and even and thus the average of two successive squares is not an integer and thus no integer is equidistant to two successive squares. - Chai Wah Wu, Jul 24 2015

Examples

			6! = 720. The nearest perfect square is 729.

Crossrefs

Cf. A055227, A260374.

Programs

  • PARI
    a(n)=round(sqrt(n!))^2 \\ Charles R Greathouse IV, Jul 23 2015
  • Python
    from gmpy2 import isqrt
A260373_list, g = [1], 1
for i in range(1, 101):
    g *= i
    s = isqrt(g)
    t = s**2
    A260373_list.append(int(t if g-t-s <= 0 else t+2*s+1)) # Chai Wah Wu, Jul 23 2015

Formula

a(n) = A055227(n)^2.
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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