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 A088651 a(n) = smallest number k such that rk-1 is prime for all r = 1 to n. 7
 3, 3, 4, 6, 6, 154770, 2894220, 2894220, 407874180, 214580145780, 9448481062020, 247236503934420, 2545206711847800, 18178612369988250180, 53792264108455702830 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Is the sequence finite? LINKS Carlos Rivera, Problems & Puzzles. EXAMPLE a(5)=6 because 1*6-1, 2*6-1, 3*6-1, 4*6-1, 5*6-1 are all prime. a(11)=9448481062020 because all eleven numbers 1*9448481062020-1, 2*9448481062020-1,3*9448481062020-1,...,10*9448481062020-1 & 11*9448481062020-1 are prime and 9448481062020 is the smallest number with such property. CROSSREFS Cf. A088652, A125838, A125839, A088250, A101779. Sequence in context: A145805 A277192 A098238 * A161019 A137901 A138095 Adjacent sequences:  A088648 A088649 A088650 * A088652 A088653 A088654 KEYWORD nonn AUTHOR Amarnath Murthy, Oct 29 2003 EXTENSIONS Corrected and extended by Ray Chandler, Nov 01 2003 More terms from Don Reble, Nov 23 2003 Entry revised by N. J. A. Sloane, Jan 05 2007 a(14)-a(15) from Jens Kruse Andersen, May 02 2008 STATUS approved

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Last modified April 21 11:02 EDT 2021. Contains 343150 sequences. (Running on oeis4.)