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