|
%I #15 Dec 25 2021 11:22:23
%S 8,10,12,14,18,22,26,30,32,36,38,40,42,50,52,58,62,68,72,78,84,86,92,
%T 94,98,100,102,108,112,114,116,120,122,124,128,130,138,146,148,152,
%U 158,162,166,170,172,176,184,186,200,212,214,216,218,222,224,226,234,250,252
%N Numbers n such that n^4+1 is an odd semiprime.
%H Hugo Pfoertner, <a href="/A096171/b096171.txt">Table of n, a(n) for n = 1..10000</a>
%e a(1)=8 because 8^4 + 1 = 4097 = 17*241;
%e a(2)=10: 10^4 + 1 = 10001 = 73*137.
%t Select[Range[2,300,2],PrimeOmega[#^4+1]==2&] (* _Harvey P. Dale_, Dec 25 2021 *)
%o (PARI) isA096171(n) = {local(m);m=n^4+1;(m%2==1)&&(bigomega(m)==2)} \\ _Michael B. Porter_, Feb 02 2010
%Y Cf. A000068 (n^4+1 is prime), A037896 (primes of the form n^4+1), A096169 ((n^4+1)/2 is prime), A069170 (primes of the form (n^4+1)/2), A096172 (largest prime factor of n^4+1), A046388.
%K nonn
%O 1,1
%A _Hugo Pfoertner_, Jun 19 2004
|
