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URL: https://oeis.org/A169965

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A169965
Numbers whose decimal expansion contains only 0's and 2's.
14
0, 2, 20, 22, 200, 202, 220, 222, 2000, 2002, 2020, 2022, 2200, 2202, 2220, 2222, 20000, 20002, 20020, 20022, 20200, 20202, 20220, 20222, 22000, 22002, 22020, 22022, 22200, 22202, 22220, 22222, 200000, 200002, 200020, 200022, 200200, 200202, 200220, 200222
OFFSET
1,2
FORMULA
a(n+1) = Sum_{k>=0} A030308(n,k)*A093136(k+1). - Philippe Deléham, Oct 16 2011
a(n) = 2 * A007088(n-1).
MATHEMATICA
Map[FromDigits, Tuples[{0, 2}, 6]] (* Paolo Xausa, Oct 30 2023 *)
PROG
(PARI) print1(0); for(d=1, 5, for(n=2^(d-1), 2^d-1, print1(", "); forstep(i=d-1, 0, -1, print1((n>>i)%2*2)))) \\ Charles R Greathouse IV, Nov 16 2011
(PARI) lista(N) = vector(N, i, fromdigits(binary(i-1)*2)); \\ Ruud H.G. van Tol, Oct 26 2024
(Haskell)
a169965 n = a169965_list !! (n-1)
a169965_list = map (* 2) a007088_list
-- Reinhard Zumkeller, Jan 10 2012
KEYWORD
nonn,base,easy
AUTHOR
N. J. A. Sloane, Aug 07 2010
STATUS
approved