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%I #14 May 24 2013 03:16:08
%S 7,19,29,37,47,59,67,79,89,97,109,113,127,139,149,157,167,179,181,199,
%T 199,211,229,239,241,257,269,277,283,293,307,317,317,337,349,359,367,
%U 379,389,397,409,419,421,439,449,457,467,479,487,499,509,509,523,523
%N Greatest prime less than 10n.
%C First repeating terms are 199, 317, 509, 523, 619, 839, 887, 1069, 1129, 1129, 1259, 1327, 1327, 1327, 1409, 1459, 1499, 1637, 1669, 1669, 1709, 1759, 1789, 1847, 1889, 1913, 1951.
%C a(n) is also the greatest prime factor among composites (A002808) below 20n. For primes of the form 20n + 1, see A141881. - Lekraj Beedassy, Jan 23 2012
%H Charles R Greathouse IV, <a href="/A122072/b122072.txt">Table of n, a(n) for n = 1..10000</a>
%t Table[Prime[PrimePi[10 n]], {n, 54}] (* _Jayanta Basu_, May 24 2013 *)
%o (PARI) a(n)=precprime(10*n) \\ _Charles R Greathouse IV_, Feb 26 2012
%K nonn,easy
%O 1,1
%A _Zak Seidov_, Oct 16 2006