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 A088584 Primes of the form n*x^n + (n-1)*x^(n-1) + . . . + x + 1 for x=3. 0

%I

%S 103,312088729,9955641160957,163142317702973500798039087,

%T 327058383882861814163660125754017,

%U 67973813526967723994124686175157751059,545249446055539622797498212423248888694512551610580463

%N Primes of the form n*x^n + (n-1)*x^(n-1) + . . . + x + 1 for x=3.

%C Sum of reciprocals = 0.009708741068395080316898549713.. Are these primes infinite?

%C The next term (a(8)) has 148 digits. - _Harvey P. Dale_, Dec 15 2018

%e 3*3^3 + 2*3^2 + 3 + 1 = 103.

%t Select[Accumulate[Join[{1},Table[n*3^n,{n,200}]]],PrimeQ] (* _Harvey P. Dale_, Dec 15 2018 *)

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

%K nonn

%O 1,1

%A _Cino Hilliard_, Nov 20 2003

%E More terms from _Harvey P. Dale_, Dec 15 2018

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Last modified January 22 02:05 EST 2020. Contains 331133 sequences. (Running on oeis4.)