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 A253016 Numbers n such that 11^phi(n) == 1 (mod n^2), where phi(n) = A000010(n). 3
 71, 142, 284, 355, 497, 710, 994, 1420, 1491, 1988, 2485, 2840, 2982, 3976, 4970, 5680, 5964, 7455, 9940, 11928, 14910, 19880, 23856, 29820, 39760, 59640, 79520, 119280, 238560, 477120 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS No further terms up to 10^9. No more terms less than 10^10. - Robert G. Wilson v, Jan 18 2015 The first 30 terms are divisible by 71. Are there any terms not divisible by 71? - Robert Israel, Dec 30 2014 By Corollary 5.9 in Agoh, Dilcher, Skula (1997), if there are no further Wieferich primes to base 11 apart from 71, then the answer is no. - Felix Fröhlich, Dec 30 2014 LINKS Table of n, a(n) for n=1..30. T. Agoh, K. Dilcher and L. Skula, Fermat Quotients for Composite Moduli, J. Num. Theory, Vol. 66, Issue 1 (1997), 29-50. MAPLE select(t -> 11 &^ numtheory:-phi(t) mod t^2 = 1, [\$1..10^6]); # Robert Israel, Dec 30 2014 MATHEMATICA a253016[n_] := Select[Range[n], PowerMod[11, EulerPhi[#], #^2] == 1 &]; a253016[500000] (* Michael De Vlieger, Dec 29 2014; modified by Robert G. Wilson v, Jan 18 2015 *) PROG (PARI) for(n=2, 1e9, if(Mod(11, n^2)^(eulerphi(n))==1, print1(n, ", "))) CROSSREFS Cf. A077816, A242958, A242959, A242960, A245529, A241977, A241978. Sequence in context: A111092 A140732 A025023 * A157921 A033224 A142178 Adjacent sequences: A253013 A253014 A253015 * A253017 A253018 A253019 KEYWORD nonn AUTHOR Felix Fröhlich, Dec 26 2014 STATUS approved

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Last modified July 14 20:04 EDT 2024. Contains 374323 sequences. (Running on oeis4.)