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A240503
Numbers k such that 5^k - 4^k - 3^k - 2^k - 1 is prime.
3
4, 8, 72, 396, 4428, 63152
OFFSET
1,1
COMMENTS
a(7) > 70000. - Giovanni Resta, Apr 09 2014
a(7) > 110000. - Michael S. Branicky, Jul 06 2024
EXAMPLE
5^4-4^4-3^4-2^4-1 = 271 is prime. Thus, 4 is a term of this sequence.
PROG
(PARI) for(n=1, 7500, if(ispseudoprime(5^n-4^n-3^n-2^n-1), print(n)))
CROSSREFS
Sequence in context: A013112 A274461 A206346 * A221484 A338314 A288956
KEYWORD
nonn,more
AUTHOR
Derek Orr, Apr 06 2014
EXTENSIONS
a(6) from Giovanni Resta, Apr 09 2014
STATUS
approved