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).

3, 4, 5, 10, 40

Offset

1,1

Links

Table of n, a(n) for n=1..5.

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)).

Cf. A000032, A000045, A121171, A001946.

Sequence in context: A136366 A123820 A261903 * A225906 A332790 A329524

Adjacent sequences: A133317 A133318 A133319 * A133321 A133322 A133323

Keyword

more,nonn

Author

Alexander Adamchuk, Oct 18 2007

Status

approved