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A084021
Product of n and its 9's complement.
4
0, 8, 14, 18, 20, 20, 18, 14, 8, 0, 890, 968, 1044, 1118, 1190, 1260, 1328, 1394, 1458, 1520, 1580, 1638, 1694, 1748, 1800, 1850, 1898, 1944, 1988, 2030, 2070, 2108, 2144, 2178, 2210, 2240, 2268, 2294, 2318, 2340, 2360, 2378, 2394, 2408, 2420, 2430, 2438
OFFSET
0,2
COMMENTS
There are infinitely many nonzero squares in this sequence; for example a(10^(4n) - 10^(2n)) = (10^n*(10^(2n)-1))^2. - David Wasserman, Dec 07 2004
LINKS
FORMULA
a(n) = n*(10^d - 1 - n), where d is the number of digits in n.
a(n) = n*A061601(n). - David Wasserman, Dec 07 2004
PROG
(PARI) {a(n) = n*(10^length(Str(n))-1-n)} \\ Seiichi Manyama, Sep 15 2019
CROSSREFS
Cf. A061601.
Sequence in context: A179186 A349081 A192045 * A138666 A072835 A367035
KEYWORD
base,easy,nonn
AUTHOR
Amarnath Murthy, May 23 2003
EXTENSIONS
More terms from David Wasserman, Dec 07 2004
a(0)=0 prepended by Seiichi Manyama, Sep 15 2019
STATUS
approved