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A329920 Smallest k such that 6*k*A121940(n)-1 and 6*k*A121940(n)+1 are twin primes.

%I A329920 #21 Jan 29 2020 05:52:34
%S A329920 1,2,2,15,36,10,13,26,30,228,24,138,520,59,110,456,700,670,146,300,
%T A329920 390,53,2335,340,159,340,65,475,785,1145,759,3557,490,169,990,1527,
%U A329920 704,3379,1426,1927,2397,600,1603,4809,9815,58,35,364,361,123,2197,4054,1867,1827,5048
%N A329920 Smallest k such that 6*k*A121940(n)-1 and 6*k*A121940(n)+1 are twin primes.
%e A329920 A121940(1)=7, 6*1*7-1=41, 41 and 43 are twin primes so a(1)=1.
%e A329920 A121940(2)=91, 6*2*91-1=1091, 1091 and 1093 are twin primes so a(2)=2.
%o A329920 (PFGW Script)
%o A329920 SCRIPT
%o A329920 DIM i,0
%o A329920 DIM j
%o A329920 DIM k,0
%o A329920 DIM n,1
%o A329920 OPENFILEOUT myf,a(n).txt
%o A329920 OPENFILEIN maf,a002476.txt
%o A329920 LABEL a
%o A329920 SET i,i+1
%o A329920 IF i>100 THEN END
%o A329920 GETNEXT j,maf
%o A329920 SET n,n*j
%o A329920 SET k,0
%o A329920 LABEL b
%o A329920 SET k,k+1
%o A329920 PRP k*6*n+1,k
%o A329920 IF ISPRP THEN GOTO c
%o A329920 GOTO b
%o A329920 LABEL c
%o A329920 PRP k*6*n-1,k
%o A329920 IF ISPRP THEN GOTO d
%o A329920 GOTO b
%o A329920 LABEL d
%o A329920 WRITE myf,k
%o A329920 GOTO a
%o A329920 (PARI) lista(nn) = {my(pp = 1); forprime (p = 1, nn, if (Mod(p, 6) == +1, pp *= p; my(k=1); while (!isprime(6*k*pp-1) || !isprime(6*k*pp+1), k++); print1(k, ", ");););} \\ _Michel Marcus_, Nov 25 2019
%Y A329920 Cf. A001359, A002476, A006512, A121940, A173937, A329336, A329916.
%K A329920 nonn
%O A329920 1,2
%A A329920 _Pierre CAMI_, Nov 24 2019