login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A178786 Express n as the sum of four squares, x^2+y^2+z^2+w^2, with x>=y>=z>=w>=0, maximizing the value of x. Then a(n) is that x. 4
0, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 3, 4, 5, 5, 5, 5, 5, 5, 5, 4, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 5, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 6, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 7, 8, 8, 8, 8, 8, 8, 8, 7, 8, 9, 9, 9, 9, 9, 9, 9, 8, 9, 9, 9, 9, 9, 9, 9, 8, 9, 9, 9, 10, 10, 10, 10, 10, 10, 10, 9, 10, 10, 10, 10, 10, 10, 10, 9, 10 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

COMMENTS

Lagrange's theorem tells us that each positive integer can be written as a sum of four squares.

LINKS

David Consiglio, Jr., Table of n, a(n) for n = 0..10000

David Consiglio, Jr., Python program

PROG

Python code :

from math import *

for nbre in range(0, 500): # or more than 500 !

....maxc4=0

....for c1 in range(0, sqrt(nbre/4)+1):

........for c2 in range(c1, sqrt(nbre/3)+1):

............for c3 in range(c2, sqrt(nbre/2)+1):

................s3=c3**2+c2**2+c1**2

................if s3<=nbre:

....................c4=sqrt(nbre-s3)

....................if int(c4)==c4 and c4>=c3:

........................if c4>maxc4:

............................maxc4=int(c4)

....print '%d, ' % maxc4,

CROSSREFS

Cf. A122922, A122923, A122924, A122925, A122926, A122927, A002330, A122921.

Analogs for 3 squares: A261904 and A261915.

Sequence in context: A204166 A227581 A263846 * A000196 A111850 A059396

Adjacent sequences:  A178783 A178784 A178785 * A178787 A178788 A178789

KEYWORD

nonn

AUTHOR

S├ębastien Dumortier, Jun 24 2011

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 30 10:26 EDT 2020. Contains 333125 sequences. (Running on oeis4.)