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A133320
Numbers k such that both A124296(k) = 5*F(k)^2 - 5*F(k) + 1 and A124297(k) = 5*F(k)^2 + 5*F(k) + 1 are prime, where F(k) = Fibonacci(k).
0
3, 4, 5, 10, 40
OFFSET
1,1
MATHEMATICA
Do[ F=Fibonacci[n]; f=5*F^2-5*F+1; g=5*F^2+5*F+1; If[ PrimeQ[f], If[ PrimeQ[g], Print[ {n, f, g} ] ] ], {n, 1, 1000} ]
CROSSREFS
Cf. A124297 (5*F(n)^2 + 5*F(n) + 1, where F(n) = Fibonacci(n)).
Cf. A124296 (5*F(n)^2 - 5*F(n) + 1, where F(n) = Fibonacci(n)).
Sequence in context: A136366 A123820 A261903 * A225906 A332790 A329524
KEYWORD
more,nonn
AUTHOR
Alexander Adamchuk, Oct 18 2007
STATUS
approved