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%I #26 Oct 26 2015 22:47:34
%S 2,4,6,6,10,8,14,10,12,12,22,14,26,16,18,18,34,20,38,22,24,24,46,26,
%T 30,28,30,30,58,32,62,34,36,36,40,38,74,40,42,42,82,44,86,46,48,48,94,
%U 50,56,52,54,54,106,56,60,58,60,60,118,62,122,64,66,66,70,68,134,70,72,72
%N a(1) = 2, a(n) = smallest number greater than n which is not coprime to n.
%H Reinhard Zumkeller, <a href="/A061228/b061228.txt">Table of n, a(n) for n = 1..10000</a>
%F a(2m) = 2m+2, a(p)= 2p if p is a prime.
%F a(n)= n + the smallest divisor (more than 1) of n.
%F a(p^k) = p^k + p if p is prime. - _Robert Israel_, Oct 21 2015
%e a(9) = 12 as 10 and 11 are coprime to 9. a(11) = 22 as 11 is a prime.
%p for n from 1 to 150 do if n=1 then printf(`%d,`,2); fi: for k from n+1 to 2*n do if igcd(n,k)>1 then printf(`%d,`,k); break; fi: od: od:
%p # alternative:
%p 2, seq(t + min(numtheory:-factorset(t)), t = 2..1000); # _Robert Israel_, Oct 21 2015
%t Table[n+First@(First/@FactorInteger[n]),{n,200}] (* _Vladimir Joseph Stephan Orlovsky_, Apr 08 2011 *)
%o (Haskell)
%o a061228 n = n + a020639 n -- _Reinhard Zumkeller_, May 06 2015
%Y Cf. A046666, A064413. Equals A020639(n) + n.
%Y Cf. A070229, A256393.
%K nonn
%O 1,1
%A _Amarnath Murthy_, Apr 23 2001
%E More terms from _James A. Sellers_, Apr 24 2001
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