OFFSET
0,1
COMMENTS
a(n+1)*(10^n)*(10^n+1) is the sum of squares of the positive even numbers not exceeding 10^n. - Graeme McRae, Aug 22 2021
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (11,-10).
FORMULA
From Vincenzo Librandi, Nov 09 2011: (Start)
a(n) = 10*a(n-1) - 3.
a(n) = 11*a(n-1) - 10*a(n-2).
G.f.: (2-5*x)/((1-x)*(1-10*x)). (End)
E.g.f.: exp(x)*(1 + 5*exp(9*x))/3. - Stefano Spezia, Nov 30 2023
MAPLE
MATHEMATICA
NestList[10#-3&, 2, 20] (* or *) LinearRecurrence[{11, -10}, {2, 17}, 20] (* Harvey P. Dale, Jan 14 2012 *)
PROG
(Magma) [(5*10^n+1)/3: n in [0..30]]; // Vincenzo Librandi, Nov 09 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Alex P. Lamoreux (Chamale_ic(AT)hotmail.com), Mar 05 2007
EXTENSIONS
Edited by Don Reble, Mar 09 2007
STATUS
approved