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%I #14 Oct 15 2020 21:22:03
%S 1,16,23,24,30,40,55,56,59,63,68,71,74,80,87,93,95,103,106,107,108,
%T 112,118,122,126,128,129,132,136,137,150,159,169,187,188,193,199,244,
%U 248,258,267,271,276,281,284,285,292,299,300,304,310,311,312,317,325,327
%N Numbers k such that prime(k) is not a twin prime and prime(prime(k)) is a twin prime.
%H Robert Israel, <a href="/A176657/b176657.txt">Table of n, a(n) for n = 1..10000</a>
%e 1 is a term because prime(1) = 2 is not a twin prime and prime(prime(1)) = 3 is a twin prime.
%p A006450 := proc(n) ithprime(ithprime(n)) ; end proc: isA176657 := proc(n) isA007510(ithprime(n)) and not isA007510(A006450(n)) ; end proc: for n from 1 to 1600 do if isA176657(n) then printf("%d,",n) ; end if; end do: # _R. J. Mathar_, Apr 26 2010
%t A006450[n_] := Prime[Prime[n]];
%t isA007510[n_] := !PrimeQ[n-2] && !PrimeQ[n+2];
%t isA176657[n_] := isA007510[Prime[n]] && !isA007510[A006450[n]];
%t Reap[For[n = 1, n <= 1000, n++, If[isA176657[n], Sow[n]]]][[2, 1]] (* _Jean-François Alcover_, Oct 15 2020, after Maple *)
%Y Cf. A006450, A007510.
%K nonn
%O 1,2
%A _Juri-Stepan Gerasimov_, Apr 23 2010
%E Corrected (29 removed, 126 inserted, 202 removed) and extended by _R. J. Mathar_, Apr 26 2010
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