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 A247094 Integers of the form (2^k + 1)/(2k + 1). 2
 1, 2, 3, 5, 27, 565, 7085, 48771, 1266205, 9099507, 17602325, 128207979, 26494256091, 11147523830125, 84179432287299, 165269711096165, 281629680514649643, 4246732448623781667, 126774939137440139965, 1925041114036033717685, 14833445639443302757131 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(A103579(n)) is a subsequence. Numbers n such that 2n + 1 divides 2^n + 1: 0, 1, 2, 5, 6, 9, 14, 18, 21, 26, 29, 30, 33, 41, 50, 53, ... LINKS Colin Barker, Table of n, a(n) for n = 1..400 EXAMPLE 1 is in this sequence because (2^1 + 1)/(2*1 + 1) = 1, 2 is in this sequence because (2^0 + 1)/(2*0 + 1) = 2, 3 is in this sequence because (2^5 + 1)/(2*5 + 1) = 3. PROG (PARI) s=[]; for(k=0, 100, t=(2^k + 1)/(2*k + 1); if(type(t)=="t_INT", s=concat(s, t))); s=vecsort(s, , 8) \\ Colin Barker, Nov 18 2014 CROSSREFS Cf. A081856, A081858, A103579, A224486, A247132. Sequence in context: A064026 A121264 A141566 * A078736 A042669 A178376 Adjacent sequences: A247091 A247092 A247093 * A247095 A247096 A247097 KEYWORD nonn AUTHOR Juri-Stepan Gerasimov, Nov 18 2014 EXTENSIONS a(19) corrected by Colin Barker, Nov 18 2014 STATUS approved

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Last modified September 8 18:41 EDT 2024. Contains 375753 sequences. (Running on oeis4.)