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 A205085 a(n) = n 5's sandwiched between two 1's. 1
 11, 151, 1551, 15551, 155551, 1555551, 15555551, 155555551, 1555555551, 15555555551, 155555555551, 1555555555551, 15555555555551, 155555555555551, 1555555555555551, 15555555555555551, 155555555555555551, 1555555555555555551, 15555555555555555551 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..100 Index entries for linear recurrences with constant coefficients, signature (11,-10). FORMULA a(0)=11, a(n) = 10*a(n-1) + 41. a(n) = (140*10^n - 41)/9 (see PARI code by Charles R Greathouse IV). a(n) = 11*a(n-1) - 10*a(n-2). - Vincenzo Librandi, Jan 23 2012 MATHEMATICA a[0]=11; a[n_]:=a[n-1]*10+41; Table[a[n], {n, 0, 44}] LinearRecurrence[{11, -10}, {11, 151}, 50] (* Vincenzo Librandi, Jan 23 2012 *) Table[10FromDigits[PadRight[{1}, n, 5]]+1, {n, 20}] (* Harvey P. Dale, May 02 2019 *) PROG (PARI) a(n)=(140*10^n-41)/9 \\ Charles R Greathouse IV, Jan 23 2012 (Magma) I:=[11, 151]; [n le 2 select I[n] else 11*Self(n-1)-10*Self(n-2): n in [1..25]]; // Vincenzo Librandi, Jan 23 2012 CROSSREFS Sequence in context: A038141 A307072 A142083 * A068646 A176365 A077577 Adjacent sequences: A205082 A205083 A205084 * A205086 A205087 A205088 KEYWORD nonn,base,easy,less AUTHOR José María Grau Ribas, Jan 22 2012 STATUS approved

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Last modified April 12 22:48 EDT 2024. Contains 371639 sequences. (Running on oeis4.)