cp's OEIS Frontend

A302097 Number of odd prime factors (with multiplicity) of generalized Fermat number 13^(2^n) + 1.

%I A302097 #9 Dec 16 2019 18:06:35
%S A302097 1,2,1,1,3,4,4,3
%N A302097 Number of odd prime factors (with multiplicity) of generalized Fermat number 13^(2^n) + 1.
%C A302097 a(8) >= 6. - _Chai Wah Wu_, Dec 09 2019
%H A302097 <a href="http://factordb.com/index.php?query=%2813%5E256%2B1%29%2F2">factordb.com query on (13^256+1)/2</a>.
%e A302097 b(n) = (13^(2^n) + 1)/2.
%e A302097 Complete factorizations:
%e A302097 b(0) = 7
%e A302097 b(1) = 5*17
%e A302097 b(2) = 14281
%e A302097 b(3) = 407865361
%e A302097 b(4) = 2657*441281*283763713
%e A302097 b(5) = 193*1601*10433*68675120456139881482562689
%e A302097 b(6) = 257*3230593*36713826768408543617*3215877717636198473712500018174097551256193
%e A302097 b(7) = 96769*2940673*P131
%o A302097 (PARI) a(n) = bigomega((13^(2^n)+1)/2)
%Y A302097 Cf. A275377, A275378, A275379, A275380, A275381, A275382, A275383, A302098.
%K A302097 nonn,hard,more
%O A302097 0,2
%A A302097 _Jeppe Stig Nielsen_, Apr 01 2018