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Search: id:A135549
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| A135549 |
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Number of bases b, 1 < b < n-1, in which n is a palindrome. |
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+0
5
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| 0, 0, 0, 0, 0, 1, 0, 1, 1, 1, 2, 0, 1, 1, 1, 2, 2, 2, 2, 0, 2, 3, 1, 1, 3, 1, 3, 2, 3, 1, 2, 2, 2, 2, 2, 1, 4, 1, 2, 1, 4, 1, 3, 1, 2, 3, 3, 0, 4, 1, 3, 3, 4, 0, 3, 3, 3, 3, 1, 1, 5, 1, 2, 4, 3, 4, 3, 2, 3, 1, 3, 1, 5, 2, 2, 2, 2, 1, 5, 0, 6, 2, 3, 1, 5, 4, 2, 1, 4, 1, 4, 3, 4, 3, 1, 1, 5, 1, 4, 3, 6, 1, 3, 0, 5
(list; graph; listen)
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OFFSET
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0,11
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COMMENT
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Every integer n is a palindrome when expressed in unary, or in base n-1 (where is will be 11). So here we assume 1 < b < n-1.
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LINKS
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T. D. Noe, Table of n, a(n) for n=0..10000
John P. Linderman, Description of A135549-A135551 and A016038
John P. Linderman, Perl program [Use the command: palin.pl]
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FORMULA
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a(n) = A065531(n)-1 = A126071(n)-2 for n>2. - T. D. Noe (noe(AT)sspectra.com), Feb 28 2008
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MATHEMATICA
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a = {0, 0, 0}; For[n = 4, n < 100, n++, c = 0; For[b = 2, b < n - 1, b++, If[IntegerDigits[n, b] == Reverse[IntegerDigits[n, b]], c++ ]]; AppendTo[a, c]]; a - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Feb 27 2008
Table[cnt=0; Do[d=IntegerDigits[n, b]; If[d==Reverse[d], cnt++ ], {b, 2, n-2}]; cnt, {n, 0, 100}] - T. D. Noe (noe(AT)sspectra.com), Feb 28 2008
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CROSSREFS
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Cf. A135550, A135551, A016038.
Cf. A016038 (non-palindromic numbers in any base 1 < b < n-1)
Sequence in context: A051160 A051159 A035697 this_sequence A124737 A121303 A166396
Adjacent sequences: A135546 A135547 A135548 this_sequence A135550 A135551 A135552
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KEYWORD
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nonn
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AUTHOR
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John P. Linderman (jpl(AT)research.att.com), Feb 26 2008, Feb 28 2008
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