

A025321


Numbers that are the sum of 3 nonzero squares in exactly 1 way.


3



3, 6, 9, 11, 12, 14, 17, 18, 19, 21, 22, 24, 26, 29, 30, 34, 35, 36, 42, 43, 44, 45, 46, 48, 49, 50, 53, 56, 61, 65, 67, 68, 70, 72, 73, 76, 78, 82, 84, 88, 91, 93, 96, 97, 104, 106, 109, 115, 116, 120, 133, 136, 140, 142, 144, 145, 157, 163, 168, 169, 172, 176, 180, 184, 190
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OFFSET

1,1


COMMENTS

It appears that all terms have the form 4^i A094740(j) for some i and j.  T. D. Noe, Jun 06 2008
This is true, because A025427(4*n) = A025427(n) for all n.  Robert Israel, Mar 09 2016


LINKS

T. D. Noe and Donovan Johnson, Table of n, a(n) for n = 1..605 (terms < 10^8, first 417 terms from T. D. Noe)
Eric Weisstein's World of Mathematics, Square Number.
Index entries for sequences related to sums of squares


MATHEMATICA

lim=20; nLst=Table[0, {lim^2}]; Do[n=a^2+b^2+c^2; If[n>0 && n<lim^2, nLst[[n]]++ ], {a, lim}, {b, a, Sqrt[lim^2a^2]}, {c, b, Sqrt[lim^2a^2b^2]}]; Flatten[Position[nLst, 1]] (* T. D. Noe, Jun 06 2008 *)


CROSSREFS

Cf. A000408, A025427.
Sequence in context: A065940 A024795 A000408 * A153238 A230193 A201462
Adjacent sequences: A025318 A025319 A025320 * A025322 A025323 A025324


KEYWORD

nonn


AUTHOR

David W. Wilson


STATUS

approved



