%I #25 Sep 22 2015 08:40:01
%S 1,2,3,4,5,12,7,16,27,50,33,72,39,56,45,64,51,108,57,100,105,154,115,
%T 288,125,286,243,392,203,690,217,416,363,544,455,864,407,836,663,1000,
%U 451,1512,559,1276,1125,1334,799,2256,931,2000,1377,1924,1007,2862,1375
%N a(1)=1. For n>1, a(n) = the smallest positive multiple of n such that phi(a(n)) >= phi(a(n-1)), where phi(m) is A000010(m).
%C A143483(n) = phi(a(n)).
%C A143480 is an analogous sequence but with phi(a(n)) > phi(a(n-1)).
%H Peter Kagey, <a href="/A143482/b143482.txt">Table of n, a(n) for n = 1..10000</a>
%e a(9) = 27 because:
%e phi(9) = 6 < 8 = phi(a(8)),
%e phi(18) = 6 < 8 = phi(a(8)),
%e phi(27) = 18 >= 8 = phi(a(8)).
%t a = t = {1}; lim = 55; Do[k = 1; While[EulerPhi[k n] < t[[n - 1]], k++]; AppendTo[a, k n]; AppendTo[t, EulerPhi[k n]], {n, 2, lim}]; a (* _Michael De Vlieger_, Sep 04 2015 *)
%o (PARI) lista(nn) = {print1(a=1, ", "); for (n=2, nn, k = 1; phia = eulerphi(a); while(eulerphi(k*n) < phia, k++); a = k*n; print1(a, ", "););} \\ _Michel Marcus_, Sep 22 2015
%Y Cf. A000010, A143480, A143483.
%K nonn
%O 1,2
%A _Leroy Quet_, Aug 19 2008
%E Extended by _Ray Chandler_, Nov 09 2008