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A073863
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a(1) = 4; a(n) = average of the largest and the smallest n-digit primes.
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0
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4, 54, 549, 5491, 54999, 549993, 5499997, 55000004, 549999972, 5499999987, 54999999998, 549999999996, 5500000000005, 55000000000005, 550000000000010, 5499999999999987, 55000000000000029, 549999999999999996
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| a(3) =(997+101)/2 = 549.
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MAPLE
| a:=n->(nextprime(10^n-1)+prevprime(10^(n+1)))/2: seq(a(n), n=1..20); (Deutsch)
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CROSSREFS
| Sequence in context: A095210 A156469 A001545 * A199022 A089205 A055774
Adjacent sequences: A073860 A073861 A073862 * A073864 A073865 A073866
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KEYWORD
| base,nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Aug 15 2002
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EXTENSIONS
| Corrected and extended by Emeric Deutsch (deutsch(AT)duke.poly.edu), Feb 25 2005
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