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A333912
Numbers k such that phi(k) is not the sum of 3 squares, where phi is the Euler totient function (A000010).
3
29, 58, 61, 77, 93, 99, 113, 122, 124, 141, 145, 154, 157, 169, 186, 188, 198, 226, 232, 237, 241, 253, 282, 287, 290, 301, 305, 314, 316, 317, 325, 338, 348, 349, 363, 369, 381, 385, 387, 413, 429, 441, 449, 465, 474, 482, 484, 488, 493, 495, 496, 506, 508, 509
OFFSET
1,1
COMMENTS
Pollack (2011) proved that the complementary sequence has asymptotic density 7/8. Therefore the asymptotic density of this sequence is 1/8.
LINKS
EXAMPLE
1 is not a term since phi(1) = 1 = 0^2 + 0^2 + 1^2 is the sum of 3 squares.
29 is a term since phi(29) = 28 is not the sum of 3 squares.
MATHEMATICA
Select[Range[500], SquaresR[3, EulerPhi[#]] == 0 &]
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Apr 09 2020
STATUS
approved