A084349 Squarefree numbers that are not the sum of two squares.

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

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: A338066 A297292 A087642 * A126003 A047556 A255053

Adjacent sequences: A084346 A084347 A084348 * A084350 A084351 A084352

Keyword

nonn

Author

Reinhard Zumkeller, Jun 21 2003

Status

approved