|
%I #10 Sep 19 2020 19:06:06
%S 3,5,7,7,23,23,43,67,71,73,127,127,151,163,173,181,199,199,229,239,
%T 257,271,293,353,383,419,419,457,463,479,487,523,571,599,601,617,631,
%U 643,643,673,733,739,739,761,821,827,827,863,881,881,887,907,937,967,1033
%N Primes of the form (p(n)-2*n)/7, where p(n)=n-th prime.
%H Harvey P. Dale, <a href="/A142340/b142340.txt">Table of n, a(n) for n = 1..1000</a>
%e If n=16, then (p(16)-2*16)/7=(53-32)/7=3=a(1).
%e If n=22, then (p(22)-2*22)/7=(79-44)/7=5=a(2).
%e If n=26, then (p(26)-2*26)/7=(101-52)/7=7=a(3).
%e If n=27, then (p(27)-2*27)/7=(103-54)/7=7=a(4).
%e If n=60, then (p(60)-2*60)/7=(281-120)/7=23=a(5), etc.
%p for n from 1 to 3000 do p := (ithprime(n)-2*n)/7 ; if type(p,'integer') then if isprime(p) then printf("%d,",p) ; end if; end if; end do: # _R. J. Mathar_, Apr 28 2010
%t Select[Table[(Prime[n]-2n)/7,{n,2000}],PrimeQ] (* _Harvey P. Dale_, Sep 19 2020 *)
%Y Cf. A000040.
%K nonn
%O 1,1
%A _Juri-Stepan Gerasimov_, Oct 07 2008
%E More terms from _R. J. Mathar_, Apr 28 2010
|
