A096171 Numbers k such that k^4+1 is an odd semiprime.

8, 10, 12, 14, 18, 22, 26, 30, 32, 36, 38, 40, 42, 50, 52, 58, 62, 68, 72, 78, 84, 86, 92, 94, 98, 100, 102, 108, 112, 114, 116, 120, 122, 124, 128, 130, 138, 146, 148, 152, 158, 162, 166, 170, 172, 176, 184, 186, 200, 212, 214, 216, 218, 222, 224, 226, 234, 250, 252

Offset: 1

Author

Hugo Pfoertner, Jun 19 2004

Keywords

• nonn

Examples

			a(1)=8 because 8^4 + 1 = 4097 = 17*241;
a(2)=10: 10^4 + 1 = 10001 = 73*137.
		

Links

• Hugo Pfoertner, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000068 (n^4+1 is prime), A037896 (primes of the form k^4+1), A096169 ((n^4+1)/2 is prime), A069170 (primes of the form (k^4+1)/2), A096172 (largest prime factor of n^4+1), A046388.

Programs

Mathematica

Select[Range[2,300,2],PrimeOmega[#^4+1]==2&] (* Harvey P. Dale, Dec 25 2021 *)

PARI

isA096171(n) = {local(m);m=n^4+1;(m%2==1)&&(bigomega(m)==2)} \\ Michael B. Porter, Feb 02 2010