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A068824
a(n) = n*c(n), where c(n) is the 10's complement of n.
1
9, 16, 21, 24, 25, 24, 21, 16, 9, 900, 979, 1056, 1131, 1204, 1275, 1344, 1411, 1476, 1539, 1600, 1659, 1716, 1771, 1824, 1875, 1924, 1971, 2016, 2059, 2100, 2139, 2176, 2211, 2244, 2275, 2304, 2331, 2356, 2379
OFFSET
1,1
LINKS
FORMULA
G.f.: -2*x^2/(1-x)^3 + (9/(1-x)^2)*Sum_{k=0..infinity} (10^(2*d)*x^(10^d)-(10^(2*d)-10^d)*x^(1+10^d)). - Robert Israel, Aug 18 2019
EXAMPLE
a(45) = 2475 as 10's complement of 45 is 100-45 = 55 and 45*55 = 2475.
MAPLE
seq((10^(1+ilog10(n))-n)*n, n=1..100); # Robert Israel, Aug 18 2019
MATHEMATICA
#*(10^(IntegerLength[#]) - #) & /@ Range[39] (* Jayanta Basu, Aug 07 2013 *)
CROSSREFS
Sequence in context: A250656 A072836 A373265 * A095961 A356295 A045911
KEYWORD
easy,nonn,base
AUTHOR
Amarnath Murthy, Mar 08 2002
STATUS
approved