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
KEYWORD
base,easy,nonn
AUTHOR
Enoch Haga, Jan 24 2004
EXTENSIONS
Edited and extended by Ray Chandler, Feb 07 2004
STATUS
approved