A112874 Numbers n such that the coefficient of x^n in (x^2-x-1)^n is prime.

3, 4, 5, 6, 7, 10, 11, 12, 26, 160, 3787, 31877

Offset: 1

Author

T. D. Noe, Sep 29 2005

Keywords

• hard
• nonn

Comments

n=31877 yields a probable prime; the others have been proved prime. These n were also found by Eric Weisstein, who found no other n<100000.

Links

• Eric Weisstein's World of Mathematics, Central Trinomial Coefficient
• Eric Weisstein's World of Mathematics, Integer Sequence Primes

Crossrefs

Cf. A098331 (coefficient of x^n in (x^2-x-1)^n).

Programs

Mathematica

Select[Range[200], PrimeQ[Coefficient[Expand[(x^2-x-1)^# ], x, # ]]&]