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a(n) = lcm(n, R(n)) / gcd(n, R(n)), where R(n) (A004086) is the digit reversal of n.
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%I #6 Mar 18 2018 04:04:45

%S 1,1,1,1,1,1,1,1,1,10,1,28,403,574,85,976,1207,18,1729,10,28,1,736,28,

%T 1300,403,24,574,2668,10,403,736,1,1462,1855,28,2701,3154,403,10,574,

%U 28,1462,1,30,736,3478,28,4606,10,85,1300,1855,30,1,3640,475,4930,5605

%N a(n) = lcm(n, R(n)) / gcd(n, R(n)), where R(n) (A004086) is the digit reversal of n.

%C a(1) = 1, a(18) = 18. Are there more terms for which a(k) = k?

%e a(12) = lcm(12,21)/gcd(12,21) = 84/3 = 28.

%t r[n_] := FromDigits[ Reverse[ IntegerDigits[n]]]; Table[ LCM[n, r[n]] / GCD[n, r[n]], {n, 1, 65}]

%K base,nonn

%O 1,10

%A _Amarnath Murthy_, May 09 2002

%E Edited by _Robert G. Wilson v_, May 10 2002