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 A115976 Numbers k that divide 2^(k-2) + 1. 2
 1, 3, 49737, 717027, 9723611, 21335267, 32390921, 38999627, 43091897, 86071337, 101848553, 102361457, 228911411, 302948067, 370219467, 393664027, 455781089, 483464027, 1040406177, 1272206987, 2371678553, 2571052241, 2648052857, 3054713937, 3597613307, 3782971499, 3917903851, 4005163577, 5419912241 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Some larger terms: 4465786944074559659, 1440261542571735083956640176981881665928575750093930787551969 LINKS Max Alekseyev, Table of n, a(n) for n = 1..708 (contains all terms below 10^15) MATHEMATICA lst = {}; Do[ If[ PowerMod[2, 2n - 3, 2n - 1] == 2n - 2, AppendTo[lst, 2n - 1]], {n, 10^9}]; lst (* Robert G. Wilson v, Apr 04 2006 *) CROSSREFS The odd elements of A244673. Cf. A006521, A006517, A069927, A067945, A067946, A067947, A068382, A068383, A014945, A014946, A014949, A092028. Sequence in context: A086829 A190722 A171365 * A340182 A178966 A175551 Adjacent sequences:  A115973 A115974 A115975 * A115977 A115978 A115979 KEYWORD nonn AUTHOR Max Alekseyev, Mar 15 2006 EXTENSIONS More terms from Robert G. Wilson v, Apr 04 2006 Terms a(24) onward from Max Alekseyev, Feb 03 2015 b-file corrected and extended by Max Alekseyev, Oct 27 2018 STATUS approved

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Last modified December 5 20:31 EST 2021. Contains 349558 sequences. (Running on oeis4.)