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Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!) A122904 Numbers n such that in Z/nZ the number of squares is strictly less than the number of invertible elements. 5 5, 7, 8, 9, 11, 13, 15, 16, 17, 19, 20, 21, 23, 24, 25, 27, 28, 29, 31, 32, 33, 35, 36, 37, 39, 40, 41, 43, 44, 45, 47, 48, 49, 51, 52, 53, 55, 56, 57, 59, 60, 61, 63, 64, 65, 67, 68, 69, 71, 72, 73, 75, 76, 77, 79, 80, 81, 83, 84, 85, 87, 88, 89, 91, 92, 93, 95, 96, 97, 99, 100 (list; graph; refs; listen; history; text; internal format) OFFSET 1,1 LINKS Ivan Neretin, Table of n, a(n) for n = 1..10000 FORMULA n such that A000224(n) < A000010(n) MATHEMATICA Select[Range@100, Length@Union@Mod[Range[#]^2, #] < EulerPhi[#] &] (* Ivan Neretin, Dec 14 2016 *) CROSSREFS Cf. A122903, A122905, A122906, A122907. Sequence in context: A171097 A166460 A118742 * A104693 A373992 A225648 Adjacent sequences: A122901 A122902 A122903 * A122905 A122906 A122907 KEYWORD nonn AUTHOR Max Alekseyev, Sep 18 2006 STATUS approved

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Last modified July 18 17:18 EDT 2024. Contains 374388 sequences. (Running on oeis4.)