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%I #12 Jan 13 2020 11:29:15
%S 1,2,6,210,30030,223092870,13082761331670030,
%T 3217644767340672907899084554130,
%U 1492182350939279320058875736615841068547583863326864530410
%N Least k such that k/phi(k) >= n, where phi is Euler's totient function.
%C These are all primorial numbers (A002110).
%C It appears that the primorial index of a(n) is A256968(n-1) for n>=1. - _Michel Marcus_, Oct 07 2019
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/TotientFunction.html">Totient Function</a>
%t Table[prod=1; i=0; While[prod<n, i++; prod=prod/(1-1/Prime[i])]; Times@@Prime[Range[i]], {n, 1, 9}]
%o (PARI) a(n) = my(p=1, i=0); while(p<n, i++; p = p/(1-1/prime(i))); prod(k=1, i, prime(k)); \\ _Michel Marcus_, Oct 07 2019
%Y Cf. A002110, A091456 (n * phi(k) < k).
%K easy,nonn
%O 1,2
%A _T. D. Noe_, Jan 09 2004
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