A225584 - OEIS

A225584

Primes in the chain of repeated application of x->2*x+3, starting at x=23.

23, 101, 829, 6653, 13309, 6815741, 436207613, 13958643709, 27917287421, 468374361246531581, 3746994889972252669, 959230691832896684029, 16093220510709943573688614909

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OFFSET

1,1

COMMENTS

Primes in A156202.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..31

MATHEMATICA

Select[NestList[2 # + 3 &, 23, 30], PrimeQ] (* or *) Select[Table[13 2^(n+1) - 3, {n, 0, 150}], PrimeQ]

PROG

(Magma) x:=23; 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 13*2^n-3]

CROSSREFS

Primes of the form k*2^m-3: A050415 (k=1), A173769 (k=5), A225582 (k=7), A225583 (k=11), this sequence (k=13); A172156 (k=100), A163589 (k=715).

Numbers of the form 13*2^m-3: A156202.

Sequence in context: A142132 A140375 A142173 * A214092 A139976 A241746

Adjacent sequences: A225581 A225582 A225583 * A225585 A225586 A225587

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, May 14 2013

STATUS

approved