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%I #11 Mar 07 2013 06:29:10
%S 5,7,13,7,5,11,7,7,5,13,5,11,7,13,13,11,5,11,13,7,23,41,19,11,5,17,17,
%T 79,13,43,7,19,13,13,13,43,67,7,13,43,31,11,113,7,5,13,59,11,5,83,19,
%U 37,7,113,29,19,23,41,97,53,79,13,29,7,5,41,19,13,11
%N Least prime p>3 such that 2^n + p*2^k - 1 and 2^n + p*2^k + 1 are twin primes for some k with n/3 < k < n+1.
%H Pierre CAMI, <a href="/A205323/b205323.txt">Table of n, a(n) for n = 1..2000</a>
%e 2^1+5*2^1-1=11 11 and 13 twin primes so a(1)=5.
%e 2^2+7*2^1-1=17 17 and 19 twin primes so a(2)=7.
%e 2^3+13*2^2-1=59 59 and 61 twin primes so a(3)=13.
%o PFGW64 from Primeform group and SCRIPTIFY
%o SCRIPT
%o DIM nn,0
%o DIM mm
%o DIM kk
%o DIMS tt
%o OPENFILEOUT myfile,twins.txt
%o LABEL loopn
%o SET nn,nn+1
%o IF nn>2000 THEN END
%o SET kk,2
%o LABEL loopk
%o SET kk,kk+1
%o SET mm,nn/3
%o LABEL loopm
%o SET mm,mm+1
%o IF mm>nn THEN GOTO loopk
%o SETS tt,%d,%d,%d,%d\ ;nn;kk;p(kk);mm
%o PRP 2^nn+p(kk)*2^mm-1,tt
%o IF ISPRIME THEN GOTO a
%o IF ISPRP THEN GOTO a
%o GOTO loopm
%o LABEL a
%o PRP 2^nn+p(kk)*2^mm+1,tt
%o IF ISPRIME THEN GOTO b
%o IF ISPRP THEN GOTO b
%o GOTO loopm
%o LABEL b
%o WRITE myfile,tt
%o GOTO loopn
%Y Cf. A205236, A205237, A205324.
%K nonn
%O 1,1
%A _Pierre CAMI_, Jan 26 2012
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