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A155918 Number of squared hypotenuses mod n in two dimensions. 5
1, 2, 3, 3, 5, 6, 7, 5, 7, 10, 11, 9, 13, 14, 15, 9, 17, 14, 19, 15, 21, 22, 23, 15, 25, 26, 21, 21, 29, 30, 31, 17, 33, 34, 35, 21, 37, 38, 39, 25, 41, 42, 43, 33, 35, 46, 47, 27, 43, 50, 51, 39, 53, 42, 55, 35, 57, 58, 59, 45, 61, 62, 49, 33, 65, 66, 67, 51, 69, 70, 71, 35, 73 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Number of images of the map (x,y) -> x^2+y^2 in Z_n.

LINKS

Michel Marcus, Table of n, a(n) for n = 1..1000

MATHEMATICA

(For[v = Table[0, {m, 1, n^2}]; m = 1; i = 0, i < n, i++, For[j = 0, j < n, j++, v[[m]] = Mod[i^2 + j^2, n]; m = m + 1]]; Length[Union[v]])

PROG

(PARI) a(n) = #Set(vector(n^2, i, ((i%n)^2 + (i\n)^2) % n)); \\ Michel Marcus, Jul 08 2017

CROSSREFS

Sequence in context: A085314 A085310 A055653 * A097248 A097247 A097246

Adjacent sequences:  A155915 A155916 A155917 * A155919 A155920 A155921

KEYWORD

mult,nonn

AUTHOR

Steven Finch, Jan 30 2009

STATUS

approved

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Last modified January 16 21:37 EST 2019. Contains 319206 sequences. (Running on oeis4.)