A087106 Primes of the form (prime(k-1)+1)*(prime(k+1)-1) + 1, k>1.

13, 61, 97, 193, 397, 1597, 1933, 9001, 12097, 14821, 18217, 21001, 31321, 37633, 74521, 91141, 96097, 122497, 168037, 211597, 266221, 478801, 605221, 719041, 760321, 781453, 808081, 861121, 915769, 1034281, 1245421

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Example

k=25: (prime(25-1)+1)*(prime(25+1)-1)=(89+1)*(101-1)=9000, as 9000+1=A000040(1118), 9001 is a term.

Mathematica

Select[Table[(Prime[n-1]+1)*(Prime[n+1]-1)+1, {n, 0, 1000}], PrimeQ] (* Vincenzo Librandi, Jul 15 2012 *)

Prog

(Magma) [p: n in [2..200] | IsPrime(p) where p is (NthPrime(n-1)+1)*(NthPrime(n+1)-1)+1]; // Vincenzo Librandi, Jul 16 2012

Crossrefs

Cf. A087105.

Sequence in context: A316309 A317264 A028874 * A142402 A140615 A086361

Adjacent sequences: A087103 A087104 A087105 * A087107 A087108 A087109

Keyword

nonn

Author

Reinhard Zumkeller, Aug 10 2003

Status

approved