A291173 - OEIS

A291173

Totient superdeficient numbers: numbers n > 1 such that s(n)/n < s(m)/m for all m < n, where s(n) is the sum of iterated phi(n) (A092693).

%I #9 Aug 31 2017 17:43:38

%S 2,42,90,210,630,1050,1470,2310,6930,16170,30030,90090,150150,210210,

%T 570570,690690,870870,2072070,3573570,3993990,4834830

%N Totient superdeficient numbers: numbers n > 1 such that s(n)/n < s(m)/m for all m < n, where s(n) is the sum of iterated phi(n) (A092693).

%C A variation of A286268 (Totient superabundant numbers).

%e The values of A092693(n)/n for n = 2, 42, 90 are 0.5, 0.452..., 0.433..., which are records of lowest values.

%t Function[s, Flatten[First@Position[s, #] & /@ Union@Rest@FoldList[Max, 0, s]]]@ Table[n/(Total@FixedPointList[EulerPhi, n] - (n + 1)), {n, 2, 10^5}]+1 (* after _Michael De Vlieger_ at A286268 and _Alonso del Arte_ at A092693 *)

%Y Cf. A092693, A286268, A291174.

%K nonn,more

%O 1,1

%A _Amiram Eldar_, Aug 19 2017