The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A173804 a(n) = (5*10^n - 41)/9 for n > 0. 4
 1, 51, 551, 5551, 55551, 555551, 5555551, 55555551, 555555551, 5555555551, 55555555551, 555555555551, 5555555555551, 55555555555551, 555555555555551, 5555555555555551, 55555555555555551, 555555555555555551 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Primes up to n=100 are 555555555551 and 5555555555551; the next prime term has 609 digits (see A056684). LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..100 Index entries for linear recurrences with constant coefficients, signature (11,-10). FORMULA a(n) = 10*a(n-1) + 41 with a(0)=-4. G.f.: x*(1+40*x)/((1-x)*(1-10*x)). - Vincenzo Librandi, Jul 05 2012 a(n) = 11*a(n-1) - 10*a(n-2). - Vincenzo Librandi, Jul 05 2012 MATHEMATICA CoefficientList[Series[(1+40*x)/((1-x)*(1-10*x)), {x, 0, 30}], x] (* Vincenzo Librandi, Jul 05 2012 *) Table[FromDigits[PadLeft[{1}, n, 5]], {n, 20}] (* or *) LinearRecurrence[ {11, -10}, {1, 51}, 20](* Harvey P. Dale, Dec 04 2021 *) PROG (MAGMA)[(5*10^n-41)/9: n in [1..20]]; // Vincenzo Librandi, Jul 05 2012 CROSSREFS Cf. A056684 (numbers n such that (5*10^(n+1)-41)/9 is prime). - Klaus Brockhaus, Feb 28 2010 Sequence in context: A142994 A251932 A319542 * A166820 A269438 A269622 Adjacent sequences:  A173801 A173802 A173803 * A173805 A173806 A173807 KEYWORD nonn,easy AUTHOR Vincenzo Librandi, Feb 25 2010 STATUS approved

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.

Last modified August 17 22:31 EDT 2022. Contains 356193 sequences. (Running on oeis4.)