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A178898 a(n) = number of ways in which n^2 can be expressed as the sum of five different squares. 3
0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 4, 3, 6, 7, 13, 7, 16, 14, 21, 21, 27, 24, 31, 35, 43, 43, 60, 51, 66, 61, 88, 83, 105, 91, 137, 116, 124, 140, 185, 143, 195, 187, 233, 197, 266, 220, 317, 283, 318, 317, 371, 331, 433, 404, 476, 450, 529, 427, 620, 543, 616 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,15

COMMENTS

a(n) ignores the order of the five squares. If we count all 5-plets whose squares sum to a square, including repetitions, then the limit as n goes to infinity of the ratio of this number to a(n) is 5/4.

LINKS

Table of n, a(n) for n=1..66.

FORMULA

a(n) = A025444(n^2). [From R. J. Mathar, Oct 18 2010]

EXAMPLE

For n=17 a(17)=3 since 17^2 can be expressed as the sum of 5 different squares in 3 ways: 17^2 = 14^2+8^2+4^2+3^2+2^2 = 13^2+8^2+6^2+4^2+2^2 = 12^2+10^2+5^2+4^2+2^2.

CROSSREFS

Sequence in context: A054239 A305424 A048680 * A296616 A143529 A261351

Adjacent sequences:  A178895 A178896 A178897 * A178899 A178900 A178901

KEYWORD

nonn

AUTHOR

Carmine Suriano, Jun 21 2010

STATUS

approved

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Last modified September 15 18:47 EDT 2019. Contains 327083 sequences. (Running on oeis4.)