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A084349 Squarefree numbers that are not the sum of two squares. 2
1, 3, 6, 7, 11, 14, 15, 19, 21, 22, 23, 30, 31, 33, 35, 38, 39, 42, 43, 46, 47, 51, 55, 57, 59, 62, 66, 67, 69, 70, 71, 77, 78, 79, 83, 86, 87, 91, 93, 94, 95, 102, 103, 105, 107, 110, 111, 114, 115, 118, 119, 123, 127, 129, 131, 133, 134, 138, 139, 141, 142, 143 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Intersection of A005117 (squarefree) and A018825. - Michel Marcus, Dec 02 2015

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Index entries for sequences related to sums of squares

EXAMPLE

A005117(10) = 14: 14 - 1^2 = 13, 14 - 2^2 = 10 and 14 - 3^3 = 5 are nonsquares, therefore 14 is a term;

A005117(9) = 13 is not a term: A020893(4) = 13 = 2^2 + 3^2.

MATHEMATICA

Prepend[Select[Range@ 144, SquareFreeQ@ # && SquaresR[2, #] == 0 &], 1] (* Michael De Vlieger, Dec 02 2015 *)

PROG

(Haskell)

a084349 n = a084349_list !! (n-1)

a084349_list = 1 : filter (\x -> all (== 0) $ map (a010052 . (x -)) $

                           takeWhile (<= x) a000290_list) a005117_list

-- Reinhard Zumkeller, Dec 11 2011

CROSSREFS

Cf. A000290, A005117, A010052, A018825, A020893.

Sequence in context: A189626 A297292 A087642 * A126003 A047556 A255053

Adjacent sequences:  A084346 A084347 A084348 * A084350 A084351 A084352

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Jun 21 2003

STATUS

approved

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Last modified May 19 13:18 EDT 2019. Contains 323393 sequences. (Running on oeis4.)