login
A173193
a(n) = (2*10^n+43)/9.
1
7, 27, 227, 2227, 22227, 222227, 2222227, 22222227, 222222227, 2222222227, 22222222227, 222222222227, 2222222222227, 22222222222227, 222222222222227, 2222222222222227, 22222222222222227, 222222222222222227
OFFSET
1,1
COMMENTS
n-1 2's followed by a 7.
FORMULA
a(n) = 10*a(n-1)-43 with n>1, a(1)=7. - Vincenzo Librandi, Dec 05 2010
a(n) = a(n-1)+2*10^(n-1) with n>1, a(1)=7. - Zak Seidov, Dec 05 2010
From Colin Barker, Jan 24 2013: (Start)
a(n) = 11*a(n-1)-10*a(n-2).
G.f.: -x*(50*x-7)/((x-1)*(10*x-1)). (End)
MATHEMATICA
Table[FromDigits[PadLeft[{7}, n, 2]], {n, 20}] (* or *) LinearRecurrence[{11, -10}, {7, 27}, 20] (* Harvey P. Dale, Jan 06 2023 *)
CROSSREFS
Sequence in context: A035081 A193257 A330621 * A196323 A003148 A033910
KEYWORD
easy,nonn
AUTHOR
Ivan Panchenko, Feb 12 2010
EXTENSIONS
More terms from Vincenzo Librandi, Feb 24 2010
STATUS
approved