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Primes in the 7th-order Fibonacci numbers A060455.
2

%I #20 May 08 2015 15:15:49

%S 7,13,97,193,769,1531,3049,6073,12097,24097,95617,379399,2998753,

%T 187339729,373174033,2949551617,184265983633,731152932481,

%U 88025699967469825543,175344042716296888429,4979552865927484193343796114081304399449

%N Primes in the 7th-order Fibonacci numbers A060455.

%C a(22) is too large to display here. It has 53 digits and is the 180th term in A060455.

%H Robert G. Wilson v, <a href="/A253333/b253333.txt">Table of n, a(n) for n = 1..34</a>

%t a={1,1,1,1,1,1,1}; step=7; lst={}; For[n=step,n<=1000,n++, sum=Plus@@a; If[PrimeQ[sum], AppendTo[lst,sum]]; a=RotateLeft[a]; a[[7]]=sum]; lst

%t With[{c=PadRight[{},7,1]},Select[LinearRecurrence[c,c,150],PrimeQ]] (* _Harvey P. Dale_, May 08 2015 *)

%o (PARI) lista(nn) = {gf = ( -1+x^2+2*x^3+3*x^4+4*x^5+5*x^6 ) / ( -1+x+x^2+x^3+x^4+x^5+x^6+x^7 ); for (n=0, nn, if (isprime(p=polcoeff(gf+O(x^(n+1)), n)), print1(p, ", ")););} \\ _Michel Marcus_, Jan 11 2015

%Y Cf. A001590, A001631, A100683, A231574, A231575, A232543, A214899, A020992, A233554, A214727, A234696, A141523, A235862, A214825, A235873, A001630, A241660, A247027, A000288, A247561, A000322, A248920, A000383, A247192, A060455, A253318.

%K nonn

%O 1,1

%A _Robert Price_, Dec 30 2014