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A161992 Numbers which squared are a sum of 3 distinct nonzero squares. 3
7, 9, 11, 13, 14, 15, 17, 18, 19, 21, 22, 23, 25, 26, 27, 28, 29, 30, 31, 33, 34, 35, 36, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 81, 82, 83, 84, 85, 86, 87 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Square roots of squares in A004432. - R. J. Mathar, Sep 22 2009

LINKS

Table of n, a(n) for n=1..70.

EXAMPLE

7^2 = 2^2 + 3^2 + 6^2. 9^2 = 1^2 + 4^2 + 8^2. 11^2 = 2^2 + 6^2 + 9^2. 15^2 = 2^2 + 5^2 + 14^2.

MAPLE

isA004432 := proc(n) local x, y, z2 ; for x from 1 do if x^2 > n then break; fi; for y from 1 to x-1 do z2 := n-x^2-y^2 ; if z2 < y^2 and z2 > 0 then if issqr(z2) then RETURN(true) ; fi; fi; od: od: false ; end:

isA161992 := proc(n) isA004432(n^2) ; end:

for n from 1 do if isA161992(n) then printf("%d\n", n) ; fi; od: # R. J. Mathar, Sep 22 2009

MATHEMATICA

lst={}; Do[Do[Do[a=(x^2+y^2+z^2)^(1/2); If[a==IntegerPart[a], AppendTo[lst, a]], {z, y+1, 2*5!}], {y, x+1, 2*5!}], {x, 5!}]; lst; q=Take[Union[%], 150]

CROSSREFS

Cf. A029747.

Sequence in context: A191883 A108815 A262536 * A167377 A004169 A295299

Adjacent sequences:  A161989 A161990 A161991 * A161993 A161994 A161995

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, Jun 24 2009

EXTENSIONS

Definition rephrased by R. J. Mathar, Sep 22 2009

STATUS

approved

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Last modified December 10 20:23 EST 2019. Contains 329909 sequences. (Running on oeis4.)