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 A214426 Numbers n palindromic in exactly four bases b, 2 <= b <= 10. 6
 8, 121, 373, 786435 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Searched up to 10^18. Rick Regan mentions these four numbers, also found by Bill Beckmann, at the end of his webpage. - T. D. Noe, Aug 18 2012 LINKS FORMULA A050812(n) = 4. EXAMPLE 8 is palindromic in bases 3, 7, 9, and 10. 121 is palindromic in bases 3, 7, 8, and 10. 373 is palindromic in bases 4, 7, 9, and 10. 786435 is palindromic in bases 2, 4, 7, and 8. MATHEMATICA n = -1; t = {}; While[Length[t] < 4, n++; If[Count[Table[s = IntegerDigits[n, m]; s == Reverse[s], {m, 2, 10}], True] == 4, AppendTo[t, n]]]; t CROSSREFS Cf. A050813, A214423, A214424, A214425 (palindromic in 0-3 bases). Sequence in context: A173774 A034669 A000848 * A281833 A299077 A298997 Adjacent sequences:  A214423 A214424 A214425 * A214427 A214428 A214429 KEYWORD nonn,base,hard AUTHOR T. D. Noe, Jul 18 2012 STATUS approved

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Last modified May 25 03:39 EDT 2022. Contains 354047 sequences. (Running on oeis4.)