OFFSET
1,2
COMMENTS
For n>=1, for these and only these numbers n, A242719(n) = prime(n)^2 + 1. Since A242719(n) >= prime(n)^2 + 1, then the equality is obtained on this and only this sequence.- Vladimir Shevelev, Sep 04 2014
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
FORMULA
EXAMPLE
prime(24)*prime(24)-2 = 89*89-2 = 7919 is prime, so n=24 belongs to the sequence.
PROG
(Haskell)
a137291 n = a137291_list !! (n-1)
a137291_list = filter ((== 1) . a010051' . a049001) [1..]
-- Reinhard Zumkeller, Jul 30 2015
(PARI) is(n, p=prime(n))=isprime(p^2-2) \\ Charles R Greathouse IV, Feb 17 2017
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Ctibor O. Zizka, Apr 05 2008
EXTENSIONS
More terms from R. J. Mathar, Apr 09 2008
Offset corrected by Reinhard Zumkeller, Jul 30 2015
STATUS
approved