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A169964 Numbers whose decimal expansion contains only 0's and 5's. 17
0, 5, 50, 55, 500, 505, 550, 555, 5000, 5005, 5050, 5055, 5500, 5505, 5550, 5555, 50000, 50005, 50050, 50055, 50500, 50505, 50550, 50555, 55000, 55005, 55050, 55055, 55500, 55505, 55550, 55555, 500000, 500005, 500050, 500055, 500500, 500505, 500550, 500555 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
FORMULA
a(n+1) = Sum_{k>=0} A030308(n,k)*A093143(k+1). - Philippe Deléham, Oct 16 2011
a(n) = 5 * A007088(n-1).
MATHEMATICA
Map[FromDigits, Tuples[{0, 5}, 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*5)))) \\ Charles R Greathouse IV, Nov 16 2011
(Haskell)
a169964 n = a169964_list !! (n-1)
a169964_list = map (* 5) a007088_list
-- Reinhard Zumkeller, Jan 10 2012
CROSSREFS
Sequence in context: A136890 A136889 A136887 * A061474 A136916 A204193
KEYWORD
nonn,base,easy
AUTHOR
N. J. A. Sloane, Aug 07 2010
STATUS
approved

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Last modified March 28 20:05 EDT 2024. Contains 371254 sequences. (Running on oeis4.)