The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A222814 Numbers (not ending in 0) which are 9 times their digit-reversal. 7

%I #12 Oct 12 2017 16:28:38

%S 9801,98901,989901,9899901,98019801,98999901,980109801,989999901,

%T 9801009801,9890198901,9899999901,98010009801,98901098901,98999999901,

%U 980100009801,980198019801,989010098901,989901989901,989999999901,9801000009801,9801989019801,9890100098901

%N Numbers (not ending in 0) which are 9 times their digit-reversal.

%C There are Fibonacci(floor((n-2)/2)) terms with n digits (this is essentially A103609). - _Ray Chandler_, Oct 12 2017

%H Ray Chandler, <a href="/A222814/b222814.txt">Table of n, a(n) for n = 1..10000</a>

%H N. J. A. Sloane, <a href="http://arxiv.org/abs/1307.0453">2178 And All That</a>, Fib. Quart., 52 (2014), 99-120.

%t okQ[t_]:=t==Reverse[t]&&First[t]!=0&&Min[Length/@Split[t]]>1; Sort[ Flatten[ (9*99)#&/@Flatten[Table[FromDigits/@Select[Tuples[{0,1},n],okQ],{n,12}]]]] (* _Harvey P. Dale_, Jul 03 2013 *)

%Y Equals 9*A001232.

%K nonn,base

%O 1,1

%A _N. J. A. Sloane_, Mar 11 2013

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 15 14:28 EDT 2024. Contains 372540 sequences. (Running on oeis4.)