login
Difference between the smallest 10^n-digit Sophie Germain prime and 10^(10^n - 1).
0

%I #5 Apr 03 2023 10:36:13

%S 1,289,44239,2222239,114862711

%N Difference between the smallest 10^n-digit Sophie Germain prime and 10^(10^n - 1).

%H G. L. Honaker, Jr. and Chris Caldwell, <a href="https://t5k.org/curios/cpage/7079.html">10000...44239 (100-digits)</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/SophieGermainPrime.html">Sophie Germain Prime</a>

%t lst = {}; Do[s = 10^(10^n - 1); n = NextPrime[s]; While[! PrimeQ[2*n + 1], n = NextPrime[n]]; AppendTo[lst, n - s], {n, 0, 2}]; lst

%Y Cf. A005384.

%K base,hard,more,nonn

%O 0,2

%A _Arkadiusz Wesolowski_, Jun 16 2013