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A138145 Palindromes formed from the reflected decimal expansion of the concatenation of 1, 1, 1 and infinite 0's. 12
1, 11, 111, 1111, 11111, 111111, 1110111, 11100111, 111000111, 1110000111, 11100000111, 111000000111, 1110000000111, 11100000000111, 111000000000111, 1110000000000111, 11100000000000111, 111000000000000111 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) is also A147596(n) written in base 2. [From Omar E. Pol, Nov 08 2008]

LINKS

Table of n, a(n) for n=1..18.

Index entries for linear recurrences with constant coefficients, signature (11,-10).

FORMULA

a(n) = 111+111*10^(n-3) for n>5. a(n) = 11*a(n-1)-10*a(n-2). G.f.: -x*(10*x^2-1)*(100*x^4+10*x^2+1) / ((x-1)*(10*x-1)). - Colin Barker, Sep 15 2013

EXAMPLE

n .... a(n)

1 .... 1

2 .... 11

3 .... 111

4 .... 1111

5 .... 11111

6 .... 111111

7 .... 1110111

8 .... 11100111

9 .... 111000111

10 ... 1110000111

11 ... 11100000111

12 ... 111000000111

13 ... 1110000000111

PROG

(PARI) Vec(-x*(10*x^2-1)*(100*x^4+10*x^2+1)/((x-1)*(10*x-1)) + O(x^100)) \\ Colin Barker, Sep 15 2013

CROSSREFS

Cf. A000533, A138144.

Cf. A138118, A138119, A138120, A138146, A138721, A138826, A147596. [From Omar E. Pol, Nov 08 2008]

Sequence in context: A090103 A061851 A247552 * A165370 A134962 A267257

Adjacent sequences:  A138142 A138143 A138144 * A138146 A138147 A138148

KEYWORD

easy,nonn,base

AUTHOR

Omar E. Pol, Mar 29 2008

EXTENSIONS

Better definition. - Omar E. Pol, Nov 16 2008

STATUS

approved

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Last modified May 21 23:51 EDT 2019. Contains 323472 sequences. (Running on oeis4.)