This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A091628 Concatenation of n 2's followed by 3. 6
 23, 223, 2223, 22223, 222223, 2222223, 22222223, 222222223, 2222222223, 22222222223, 222222222223, 2222222222223, 22222222222223, 222222222222223, 2222222222222223, 22222222222222223, 222222222222222223 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Sequence arising in Farideh Firoozbakht's solution to Prime Puzzle 251; 23 is the only pointer prime (A089823) not containing the digit "1". LINKS Tanya Khovanova, Recursive Sequences Carlos Rivera's Prime Puzzles and Problems Connection, Puzzle 251, Pointer primes Index entries for linear recurrences with constant coefficients, signature (11,-10). FORMULA a(n) = (10^(n+1) - 1)/9*2 + 1. a(n) = 10*a(n-1) - 7, with a(1)=23. - Vincenzo Librandi, Nov 16 2010 From Colin Barker, May 06 2012: (Start) a(n) = 11*a(n-1) - 10*a(n-2). G.f.: x*(23-30*x)/((1-x)*(1-10*x)). (End) PROG (MAGMA) [ n eq 1 select 23 else 10*Self(n-1)-7: n in [1..17] ]; CROSSREFS Cf. A089823, A091629, A091630, A091631, A091632. Sequence in context: A038514 A244766 A125386 * A126544 A272796 A285552 Adjacent sequences:  A091625 A091626 A091627 * A091629 A091630 A091631 KEYWORD base,easy,nonn AUTHOR Enoch Haga, Jan 24 2004 EXTENSIONS Edited and extended by Ray Chandler, Feb 07 2004 STATUS approved

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

Last modified October 23 05:56 EDT 2019. Contains 328335 sequences. (Running on oeis4.)