A056525 - OEIS

A056525

Palindromes with odd number of digits.

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)

OFFSET

1,2

COMMENTS

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]

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Index entries for sequences related to final digits of numbers

FORMULA

a(n) = floor[n/10]*10^A055642(n)+A004086(n)

MATHEMATICA

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 *)

PROG

(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

CROSSREFS

Cf. A002113, A004086, A056524.

Sequence in context: A052426 A240237 A056142 * A071272 A083851 A071275

Adjacent sequences: A056522 A056523 A056524 * A056526 A056527 A056528

KEYWORD

base,easy,nonn

AUTHOR

Henry Bottomley, Jun 16 2000

STATUS

approved