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 A196509 Largest palindrome formed by using n single digit numbers and the operators +, -, * and / where concatenation is not allowed. 0
 9, 11, 343, 747, 6556, 65856, 405504, 4251524, 8847488 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS This puzzle is easily trivial if exponentation or concatenation is allowed. Best known results for a(10)..a(15) are 88499488, 846747648, 4095995904, 23613431632, 68899199886, 633498894336. Erich Friedman solved and proved most of these terms. LINKS Erich Friedman, Problem of the month June 1999 EXAMPLE 11 = 9 + 2 343 = 7 * 7 * 7 747 = 9 * (9 * 9 + 2) 6556 = 9 * 9 * 9 * 9 - 5 65856 = 3 * 7 * 7 * 8 * 8 * 8 405504 = 8 * 8 * 8 * 8 * 9 * (9 + 2) 4251524 = 8 * 9 * 9 * 9 * 9 * 9 * 9 - 4 8847488 = 8 * 8 * (5 * 6 * 8 * 8 * 8 * 9 + 2) CROSSREFS Cf. A002113. Sequence in context: A146366 A146603 A159003 * A124606 A110647 A032687 Adjacent sequences:  A196506 A196507 A196508 * A196510 A196511 A196512 KEYWORD nonn,base,more AUTHOR Kausthub Gudipati, Oct 03 2011 STATUS approved

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