A225583 - OEIS

%I #23 Sep 08 2022 08:46:05

%S 19,41,173,349,701,11261,45053,180221,184549373,738197501,5905580029,

%T 188978561021,6192449487634429,49539595901075453,99079191802150909,

%U 25364273101350633469,811656739243220271101,3486039150627630854115933814781

%N Primes in the chain of repeated application of x->2*x+3, starting at x=19.

%C Primes in A156198.

%H Vincenzo Librandi, <a href="/A225583/b225583.txt">Table of n, a(n) for n = 1..37</a>

%t Select[NestList[2 # + 3 &, 19, 30], PrimeQ] (* or *) Select[Table[11 2^n - 3, {n, 0, 150}], PrimeQ]

%o (Magma) x:=19; a:=[n eq 1 select x else 2*Self(n-1)+3: n in [1..200]]; [a[i]: i in [1..#a] | IsPrime(a[i])]; /* or */ [a: n in [0..150] | IsPrime(a) where a is 11*2^n-3];

%Y Primes of the form k*2^m-3: A050415 (k=1), A173769 (k=5), A225582 (k=7), this sequence (k=11), A225584 (k=13); A172156 (k=100), A163589 (k=715).

%Y Numbers of the form 11*2^m-3: A156198.

%K nonn

%O 1,1

%A _Vincenzo Librandi_, May 14 2013