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a(n) = lcm(A020639(n), A006530(n)).
2

%I #16 Mar 30 2024 02:34:25

%S 1,2,3,2,5,6,7,2,3,10,11,6,13,14,15,2,17,6,19,10,21,22,23,6,5,26,3,14,

%T 29,10,31,2,33,34,35,6,37,38,39,10,41,14,43,22,15,46,47,6,7,10,51,26,

%U 53,6,55,14,57,58,59,10,61,62,21,2,65,22,67,34,69,14,71,6,73,74,15,38,77

%N a(n) = lcm(A020639(n), A006530(n)).

%H Enrique PĂ©rez Herrero, <a href="/A088835/b088835.txt">Table of n, a(n) for n = 1..10000</a>

%t Map[LCM[#[[1,1]], #[[-1,1]]] &, FactorInteger[Range[100]]] (* _Paolo Xausa_, Mar 29 2024 *)

%o (PARI) a(n) = if (n==1, 1, my(f=factor(n)[,1]~); lcm(vecmin(f), vecmax(f))); \\ _Michel Marcus_, Mar 15 2018

%Y Cf. A020639, A006530, A066048, A007947, A062953, A015052, A015053, A053166.

%K nonn

%O 1,2

%A _Labos Elemer_, Oct 31 2003