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A056525
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Palindromes with odd number of digits.
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5
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1, 2, 3, 4, 5, 6, 7, 8, 9, 101, 111, 121, 131, 141, 151, 161, 171, 181, 191, 202, 212, 222, 232, 242, 252, 262, 272, 282, 292, 303, 313, 323, 333, 343, 353, 363, 373, 383, 393, 404, 414, 424, 434, 444, 454, 464, 474, 484, 494, 505, 515, 525, 535, 545, 555, 565
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,2
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COMMENTS
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Concatenation of all but final digits of n with reverse of n (keeping leading zeros in the reverse)
A178788(a(n)) = 0 for n > 9. [From Reinhard Zumkeller, Jun 30 2010]
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LINKS
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Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
Index entries for sequences related to final digits of numbers
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FORMULA
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a(n) = floor[n/10]*10^A055642(n)+A004086(n)
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MATHEMATICA
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Join[Range[9], Table[FromDigits[Join[x=IntegerDigits[n], Reverse[Drop[x, -1]]]], {n, 10, 56}]] (* Jayanta Basu, May 29 2013 *)
Select[Flatten[Table[Range[10^n, 10^(n+1)-1], {n, 0, 2, 2}]], PalindromeQ] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Aug 21 2020 *)
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PROG
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(Haskell)
a056525 n = a056525_list !! (n-1)
a056525_list = [1..9] ++ [read (ns ++ [z] ++ reverse ns) |
n <- [1..], let ns = show n, z <- "0123456789"]
-- Reinhard Zumkeller, Dec 28 2011
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CROSSREFS
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Cf. A002113, A004086, A056524.
Sequence in context: A052426 A240237 A056142 * A071272 A083851 A071275
Adjacent sequences: A056522 A056523 A056524 * A056526 A056527 A056528
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KEYWORD
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base,easy,nonn
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AUTHOR
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Henry Bottomley, Jun 16 2000
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STATUS
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approved
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