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 A260312 Palindromic beastly primes that begin and end with digit '1'. 1
 16661, 1000000000000066600000000000001, 10000000000000000000000000000000000000000006660000000000000000000000000000000000000000001 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The next term a(4) contains 1017 digits, and is too large to include in data section. LINKS Tony Padilla and Brady Haran, The Most Evil Number, Numberphile video (2018) EXAMPLE a(1) = 16661 is a palindromic prime that contains the beastly number '666' and begins and ends with digit 1. a(2) = 1000000000000066600000000000001 is palindromic prime that contains the beastly number '666' and begins and ends with digit 1. MAPLE A260312:= n-> ((1*10^(n + 2) + 666)*10^n + 1 ): select(isprime, [seq((A260312 (n), n=1..100))]); MATHEMATICA Select[Table[(1*10^(n + 2) + 666)*10^n + 1, {n, 1000}], PrimeQ] 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 *) PROG (PARI) for(n=1, 500, k=((1*10^(n + 2) + 666)*10^n + 1 ); if(isprime(k), print1(k, ", "))); (MAGMA)  [k: n in [1..1000] | IsPrime(k) where k is ((1*10^(n + 2) + 666)*10^n + 1 )]; CROSSREFS Cf. A046720, A051003, A131645, A186086. Sequence in context: A196023 A108843 A232449 * A224572 A186311 A181098 Adjacent sequences:  A260309 A260310 A260311 * A260313 A260314 A260315 KEYWORD nonn,base,less AUTHOR K. D. Bajpai, Jul 22 2015 STATUS approved

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Last modified May 11 21:35 EDT 2021. Contains 343808 sequences. (Running on oeis4.)