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A066857 Smallest number k such that n! - k is a square 5
0, 1, 2, 8, 20, 44, 140, 320, 476, 3584, 12311, 4604, 74879, 414119, 2071775, 5703551, 11551671, 45680444, 442548224, 1960632176, 2657058876, 24923993276, 130518272975, 1478154932316, 5446454455004, 38610655379975 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Sequence is not monotonic: a(n) < a(n-1) for n = 12, 71, 90, 143, 145, 151, 172, 218, 257. - Zak Seidov, Jun 25 2013

LINKS

T. D. Noe, Table of n, a(n) for n = 1..100

FORMULA

a(n) = A053186(n!) = n!-A048760(n!) = n!-floor(sqrt(n!))^2 = n!-A055226(n)^2.

EXAMPLE

a(10) = 3628800 - 1904 * 1904 = 3628800 - 3625216 = 3584.

MATHEMATICA

Table[n! - Floor[Sqrt[n! ]]^2, {n, 1, 27}]

PROG

(PARI) a(n)=my(N=n!); N-sqrtint(N)^2 \\ Charles R Greathouse IV, Jun 25 2013

CROSSREFS

Cf. A068869.

Sequence in context: A296954 A203604 A240940 * A146168 A058405 A133326

Adjacent sequences:  A066854 A066855 A066856 * A066858 A066859 A066860

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Jan 21, 2002

EXTENSIONS

More terms from Vladeta Jovovic, Mar 21 2002

Edited by Robert G. Wilson v and N. J. A. Sloane, Mar 22 2002

STATUS

approved

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Last modified July 5 23:36 EDT 2020. Contains 335475 sequences. (Running on oeis4.)