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A086947
Numbers k such that Reverse(k+9) = 3.
4
21, 291, 2991, 29991, 299991, 2999991, 29999991, 299999991, 2999999991, 29999999991, 299999999991, 2999999999991, 29999999999991, 299999999999991, 2999999999999991, 29999999999999991, 299999999999999991
OFFSET
1,1
COMMENTS
Reverse(a(n)) = A086948(n).
If k is in this sequence then Reverse(k) = (2/3)*k - 2. Also A101703 is the sequence of all numbers k such that Reverse(k) = (2/3)*k - 2. So this sequence is a subsequence of A101703. - Farideh Firoozbakht, Dec 30 2004
FORMULA
a(n) = 3*(10^n - 3).
From Chai Wah Wu, Aug 01 2020: (Start)
a(n) = 11*a(n-1) - 10*a(n-2) for n > 2.
G.f.: x*(60*x + 21)/((x - 1)*(10*x - 1)). (End)
MATHEMATICA
Table[3*(10^n-3), {n, 17}]
Table[FromDigits[PadRight[{3}, n, 0]], {n, 2, 20}]-9 (* Harvey P. Dale, Nov 27 2012 *)
PROG
(Magma) [3*(10^n-3): n in [1..25] ]; // Vincenzo Librandi, Aug 22 2011
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Ray Chandler, Jul 24 2003
STATUS
approved