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 A062173 a(n) = 2^(n-1) mod n. 25
 0, 0, 1, 0, 1, 2, 1, 0, 4, 2, 1, 8, 1, 2, 4, 0, 1, 14, 1, 8, 4, 2, 1, 8, 16, 2, 13, 8, 1, 2, 1, 0, 4, 2, 9, 32, 1, 2, 4, 8, 1, 32, 1, 8, 31, 2, 1, 32, 15, 12, 4, 8, 1, 14, 49, 16, 4, 2, 1, 8, 1, 2, 4, 0, 16, 32, 1, 8, 4, 22, 1, 32, 1, 2, 34, 8, 9, 32, 1, 48, 40, 2, 1, 32, 16, 2, 4, 40, 1, 32, 64, 8, 4, 2, 54, 32, 1, 58, 58, 88, 1, 32, 1, 24, 46 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,6 COMMENTS If p is an odd prime then a(p)=1. However, a(n) is also 1 for pseudoprimes to base 2 such as 341. LINKS Antti Karttunen, Table of n, a(n) for n = 1..101101 (first 1000 terms from Harry J. Smith) EXAMPLE a(5) = 2^(5-1) mod 5 = 16 mod 5 = 1. MATHEMATICA Array[Mod[2^(# - 1), #] &, 105] (* Michael De Vlieger, Jul 01 2018 *) PROG (PARI) A062173(n) = if(1==n, 0, lift(Mod(2, n)^(n-1))); \\ Antti Karttunen, Jul 01 2018 (Haskell) import Math.NumberTheory.Moduli (powerMod) a062173 n = powerMod 2 (n - 1) n  -- Reinhard Zumkeller, Oct 17 2015 CROSSREFS Cf. A000079, A001567, A015910, A015919, A062172, A082495, A257531, A305890. Cf. A176997 (after the initial term, gives the positions of ones). Sequence in context: A293808 A276689 A091453 * A004558 A129699 A002349 Adjacent sequences:  A062170 A062171 A062172 * A062174 A062175 A062176 KEYWORD nonn AUTHOR Henry Bottomley, Jun 12 2001 EXTENSIONS More terms from Antti Karttunen, Jul 01 2018 STATUS approved

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Last modified September 21 13:37 EDT 2019. Contains 327253 sequences. (Running on oeis4.)