A088579 Primes of the form n*x^n + (n-1)*x^(n-1) + . . . + x + 1 for x=2.

3, 11, 643, 425987, 1909526242005090307

Offset

1,1

Comments

Sum of reciprocals = 0.4257999816852453227652727311..

Next term is too large to include.

Links

Michel Marcus, Table of n, a(n) for n = 1..9

Example

2*2^2 + 1*2 + 1 = 11 is prime.

Mathematica

Select[Table[1+Sum[k 2^k, {k, n}], {n, 1000}], PrimeQ] (* T. D. Noe, Nov 15 2006 *)

Prog

(PARI) polypn2(n, p) = { my(x=n, y=1); for(m=1, p, y=y+m*x^m; ); return(y) }
trajpolyp(n1, k) = { my(s=0); for(x1=0, n1, y1 = polypn2(k, x1); if(isprime(y1), print1(y1, ", "); s+=1.0/y1; ) ); }
trajpolyp(500, 2)

Crossrefs

Cf. A055469 (for x=1), A088584 (for x=3), A088583 (for x=4).

Sequence in context: A337415 A264725 A374558 * A344946 A368618 A374718

Adjacent sequences: A088576 A088577 A088578 * A088580 A088581 A088582

Keyword

nonn

Author

Cino Hilliard, Nov 20 2003

Extensions

Corrected by T. D. Noe and Don Reble, Nov 15 2006

Status

approved