%I #7 Jan 31 2023 14:20:00
%S 2,1,48,1,30,25,33,12,30,6,117,22,471,119,255,98,180,29,153,48,399,
%T 135,267,20,426,320,213,391,714,216,1395,148,915,65,2703,65,525,364,
%U 573,173,240,1239,657,205,135,30,1080,82,1056,604,3102,148,279,661,1962,435,306
%N a(n) is the least k such that k*2^n*(2^n-1)-1 and k*2^n*(2^n-1)+1 are twin primes.
%e 2*2^1*(2^1-1)-1 = 3 and 2*2^1*(2^1-1)+1 = 5, 3 and 5 twin primes so a(1)=2.
%o (PARI) a(n) = my(k=1); while(!(isprime(k*2^n*(2^n-1)-1) && isprime(k*2^n*(2^n-1)+1)), k++); k; \\ _Michel Marcus_, Jan 31 2023
%K nonn
%O 1,1
%A _Pierre CAMI_, Nov 19 2004
%E Name edited by _Michel Marcus_, Jan 31 2023