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A110397
a(n) = (10^k - n)(10^k + n), where k is the number of digits in n.
1
99, 96, 91, 84, 75, 64, 51, 36, 19, 9900, 9879, 9856, 9831, 9804, 9775, 9744, 9711, 9676, 9639, 9600, 9559, 9516, 9471, 9424, 9375, 9324, 9271, 9216, 9159, 9100, 9039, 8976, 8911, 8844, 8775, 8704, 8631, 8556, 8479, 8400, 8319, 8236, 8151, 8064, 7975
OFFSET
1,1
LINKS
EXAMPLE
a(3)=(10-3)(10+3)=91; a(11)=(100+11)(100-11)=111*89=9879.
MAPLE
s:=proc(m) nops(convert(m, base, 10)) end: a:=n->(10^(s(n))-n)*(10^(s(n))+n): seq(a(n), n=1..55); # s gives number of digits # Emeric Deutsch, Aug 01 2005
MATHEMATICA
Table[Times@@(10^IntegerLength[n]+{n, -n}), {n, 50}] (* Harvey P. Dale, May 31 2015 *)
CROSSREFS
Sequence in context: A305046 A316732 A033419 * A298509 A185504 A304009
KEYWORD
base,easy,nonn
AUTHOR
Amarnath Murthy, Jul 29 2005
EXTENSIONS
More terms from Emeric Deutsch, Aug 01 2005
STATUS
approved