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A091680
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Smallest number whose base 4 Reverse and Add! trajectory (presumably) contains exactly n base 4 palindromes, or -1 if there is no such number.
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2
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290, 78, 18, 6, 3, 36, 21, 19, 7, 8, 4, 2, 1, -1, -1, -1, -1, -1, -1, -1, -1
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| Conjecture 1: For each k > 0 the trajectory of k eventually leads to a term in the trajectory of some j which belongs to A075421, i.e. whose trajectory (presumably) never leads to a palindrome. Conjecture 2: There is no k > 0 such that the trajectory of k contains more than twelve palindromes, i.e. a(n) = -1 for n > 12.
Base 4 analogue of A077594.
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LINKS
| Index entries for sequences related to Reverse and Add!
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EXAMPLE
| a(4) = 3 since the trajectory of 3 contains the four palindromes 3, 15, 975, 64575 (3, 33, 33033, 3330333 in base 4) and at 20966400 joins the trajectory of 318 = A075421(2) and the trajectories of 1 (A035524) and 2 do not contain
exactly four palindromes.
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CROSSREFS
| Cf. A075299, A035524, A014192, A075420, A075421, A077594.
Sequence in context: A013761 A013883 A180701 * A129245 A186553 A075420
Adjacent sequences: A091677 A091678 A091679 * A091681 A091682 A091683
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KEYWORD
| base,sign
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AUTHOR
| Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Jan 28 2004
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