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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
OFFSET
0,2
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
Sequence in context: A029172 A240864 A241322 * A161052 A161256 A161281
KEYWORD
nonn,hard,more
AUTHOR
EXTENSIONS
a(9) was found by Nestor de Araújo Melo and Geoffrey Reynolds (2008)
STATUS
approved