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Numbers k such that (k-3)/2 is prime.
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%I #13 Mar 24 2023 03:02:41

%S 7,9,13,17,25,29,37,41,49,61,65,77,85,89,97,109,121,125,137,145,149,

%T 161,169,181,197,205,209,217,221,229,257,265,277,281,301,305,317,329,

%U 337,349,361,365,385,389,397,401,425,449,457,461,469,481,485,505,517,529

%N Numbers k such that (k-3)/2 is prime.

%F a(n) = 2*prime(n) + 3. - _Zak Seidov_, May 12 2007

%e For n=7, (7-3)/2 = 2 which is prime so 7 is the first entry.

%t Select[Range[550],PrimeQ[(#-3)/2]&] (* _Harvey P. Dale_, Feb 09 2011 *)

%o (PARI) g(m) = forprime(p=2,m,n=2*p+3;print1(n","))

%Y Cf. A000040.

%K easy,nonn

%O 1,1

%A _Cino Hilliard_, May 11 2007, May 17 2007