# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a138145 Showing 1-1 of 1 %I A138145 #18 Aug 09 2024 02:18:59 %S A138145 1,11,111,1111,11111,111111,1110111,11100111,111000111,1110000111, %T A138145 11100000111,111000000111,1110000000111,11100000000111, %U A138145 111000000000111,1110000000000111,11100000000000111,111000000000000111 %N A138145 Palindromes formed from the reflected decimal expansion of the concatenation of 1, 1, 1 and infinite 0's. %C A138145 a(n) is also A147596(n) written in base 2. - _Omar E. Pol_, Nov 08 2008 %H A138145 Paolo Xausa, Table of n, a(n) for n = 1..995 %H A138145 Index entries for linear recurrences with constant coefficients, signature (11,-10). %F A138145 From _Colin Barker_, Sep 15 2013: (Start) %F A138145 a(n) = 111+111*10^(n-3) for n>5. %F A138145 a(n) = 11*a(n-1)-10*a(n-2). %F A138145 G.f.: -x*(10*x^2-1)*(100*x^4+10*x^2+1) / ((x-1)*(10*x-1)). (End) %e A138145 n .... a(n) %e A138145 1 .... 1 %e A138145 2 .... 11 %e A138145 3 .... 111 %e A138145 4 .... 1111 %e A138145 5 .... 11111 %e A138145 6 .... 111111 %e A138145 7 .... 1110111 %e A138145 8 .... 11100111 %e A138145 9 .... 111000111 %e A138145 10 ... 1110000111 %e A138145 11 ... 11100000111 %e A138145 12 ... 111000000111 %e A138145 13 ... 1110000000111 %t A138145 Table[If[n < 7, (10^n - 1)/9, 111 + 111*10^(n-3)], {n, 25}] (* or *) %t A138145 LinearRecurrence[{11, -10}, {1, 11, 111, 1111, 11111, 111111, 1110111}, 25] (* _Paolo Xausa_, Aug 08 2024 *) %o A138145 (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 %Y A138145 Cf. A000533, A138144. %Y A138145 Cf. A138118, A138119, A138120, A138146, A138721, A138826, A147596. [From _Omar E. Pol_, Nov 08 2008] %K A138145 easy,nonn,base %O A138145 1,2 %A A138145 _Omar E. Pol_, Mar 29 2008 %E A138145 Better definition from _Omar E. Pol_, Nov 16 2008 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE