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 A131645 Beastly primes (version 2): primes containing 666 as a substring. 10
 6661, 16661, 26669, 46663, 56663, 66601, 66617, 66629, 66643, 66653, 66683, 66697, 76667, 96661, 96667, 106661, 106663, 106669, 116663, 146669, 166601, 166603, 166609, 166613, 166619, 166627, 166631, 166643, 166657, 166667, 166669, 166679 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS These are the primes among the beastly numbers A051003. There are several other definitions of beastly primes (see cross-references). Asymptotic density n/log(n), since almost all primes are of this form. LINKS Charles R Greathouse IV and Harry J. Smith, Table of n, a(n) for n = 1..20000 Tony Padilla and Brady Haran, The Most Evil Number, Numberphile video (2018) FORMULA a(n) ~ n log n. - Charles R Greathouse IV, Oct 13 2015 MATHEMATICA Select[Range[300000], StringFreeQ[ToString[ # ], "666"] == False && PrimeQ[ # ] &] Select[Prime[Range[300000]], !StringFreeQ[ToString[ # ], "666"]&] (* Zak Seidov, Jan 09 2009 *) PROG (PARI) digitsIn(x) = 1 + log(x)\log(10) allocatemem(932245000); default(primelimit, 4294965247); m=1; forprime (p=6660, 68466670, d=digitsIn(p); for (i=1, d-3, t=10^i; u=p\t; x=u-(u\1000)*1000; if (x==666, print(m, " ", p); write("b131645.txt", m, " ", p); m++; break))) \\ Harry J. Smith, Jan 11 2009 CROSSREFS Cf. A051003, A186086, A046720, A138563, A232448, A321001. Sequence in context: A060792 A119519 A233661 * A186086 A236733 A015310 Adjacent sequences:  A131642 A131643 A131644 * A131646 A131647 A131648 KEYWORD base,nonn AUTHOR Tanya Khovanova, Sep 08 2007 EXTENSIONS Definition corrected by Arkadiusz Wesolowski, Feb 12 2011 Edited by N. J. A. Sloane, Feb 12 2011 STATUS approved

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Last modified October 20 07:33 EDT 2019. Contains 328252 sequences. (Running on oeis4.)