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 A275380 Number of odd prime factors (with multiplicity) of generalized Fermat number 7^(2^n) + 1. 2
 0, 2, 1, 2, 2, 3, 3, 5, 3, 6 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS FORMULA a(n) = A001222(A078304(n)) for n > 0. - Felix Fröhlich, Jul 25 2016 EXAMPLE b(n) = (7^(2^n) + 1)/2. Complete Factorizations b(0) = 2*2 b(1) = 5*5 b(2) = 1201 b(3) = 17*169553 b(4) = 353*47072139617 b(5) = 7699649*134818753*531968664833 b(6) = 35969*1110623386241*15266848196793556098085000332888634369 b(7) = 257*769*197231873*6856531741041792239054980342217258517995521*P52 b(8) = 28667393*126575155274810369*P192 b(9) = 13313*943558259713*        275102002206713516320479233*1338330888777063359811677099009*        656929861401793262700329631944023570433*P321 CROSSREFS Cf. A078304, A273948. Sequence in context: A029172 A240864 A241322 * A161052 A161256 A161281 Adjacent sequences:  A275377 A275378 A275379 * A275381 A275382 A275383 KEYWORD nonn,hard,more AUTHOR Arkadiusz Wesolowski, Jul 25 2016 EXTENSIONS a(9) was found by Nestor de Araújo Melo and Geoffrey Reynolds (2008) STATUS approved

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Last modified May 12 23:35 EDT 2021. Contains 343829 sequences. (Running on oeis4.)