cp's OEIS Frontend

A260312 Palindromic beastly primes that begin and end with digit '1'.

%I A260312 #19 Sep 08 2022 08:46:13
%S A260312 16661,1000000000000066600000000000001,
%T A260312 10000000000000000000000000000000000000000006660000000000000000000000000000000000000000001
%N A260312 Palindromic beastly primes that begin and end with digit '1'.
%C A260312 The next term a(4) contains 1017 digits, and is too large to include in data section.
%H A260312 Tony Padilla and Brady Haran, <a href="https://www.youtube.com/watch?v=zk_Q9y_LNzg">The Most Evil Number</a>, Numberphile video (2018)
%e A260312 a(1) = 16661 is a palindromic prime that contains the beastly number '666' and begins and ends with digit 1.
%e A260312 a(2) = 1000000000000066600000000000001 is palindromic prime that contains the beastly number '666' and begins and ends with digit 1.
%p A260312 A260312:= n-> ((1*10^(n + 2) + 666)*10^n + 1 ): select(isprime, [seq((A260312 (n), n=1..100))]);
%t A260312 Select[Table[(1*10^(n + 2) + 666)*10^n + 1, {n, 1000}], PrimeQ]
%t A260312 Select[Table[FromDigits[Join[{1},PadRight[{},n,0],{6,6,6},PadRight[ {},n,0],{1}]],{n,0,50}],PrimeQ] (* _Harvey P. Dale_, Jul 09 2017 *)
%o A260312 (PARI) for(n=1, 500, k=((1*10^(n + 2) + 666)*10^n + 1 ); if(isprime(k), print1(k, ", ")));
%o A260312 (Magma)  [k: n in [1..1000] | IsPrime(k) where k is ((1*10^(n + 2) + 666)*10^n + 1 )];
%Y A260312 Cf. A046720, A051003, A131645, A186086.
%K A260312 nonn,base,less
%O A260312 1,1
%A A260312 _K. D. Bajpai_, Jul 22 2015