id:A114255 - OEIS Search Results

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Numbers that are nontrivial (3 digits or more) palindromes when expressed in some base 2 or greater.

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2

5, 7, 9, 10, 13, 15, 16, 17, 20, 21, 23, 25, 26, 27, 28, 29, 31, 33, 34, 36, 37, 38, 40, 41, 42, 43, 45, 46, 49, 50, 51, 52, 55, 56, 57, 59, 61, 62, 63, 64, 65, 67, 68, 71, 72, 73, 74, 78, 80, 81, 82, 83, 85, 86, 88, 89, 91, 92, 93, 97, 98, 99, 100, 101, 104, 105, 107, 109 (list; graph; listen)

	OFFSET	`1,1`
	COMMENT	`All integers are trivially palindromes in base 1. All integers n are trivially 2-digit palindromes because they can be represented as "11" in base n-1.`
	EXAMPLE	`5 is present because the palindrome (101 base 2) = 5; 803 is present because (30203 base 4) = 803.`
	PROGRAM	-- Haskell isPalindrome s = (s == reverse s) digits 0 _ = [] digits n b = n `rem` b : digits (n `quot` b) b check n = any isPalindrome $ takeWhile (\x -> length x > 2) $ map (digits n) [2..] main = mapM print $ filter check [1..]
	CROSSREFS	`Cf. A002113.` `Adjacent sequences: A114252 A114253 A114254 this_sequence A114256 A114257 A114258` `Sequence in context: A037084 A018935 A039501 this_sequence A138579 A109624 A002342`
	KEYWORD	`easy,nonn`
	AUTHOR	`Jason Orendorff (jason.orendorff(AT)gmail.com), Feb 05 2006`

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Last modified October 13 20:18 EDT 2008. Contains 145016 sequences.

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