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).

2, 42, 90, 210, 630, 1050, 1470, 2310, 6930, 16170, 30030, 90090, 150150, 210210, 570570, 690690, 870870, 2072070, 3573570, 3993990, 4834830

Offset

1,1

Comments

A variation of A286268 (Totient superabundant numbers).

Links

Table of n, a(n) for n=1..21.

Example

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

Mathematica

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 *)

Crossrefs

Cf. A092693, A286268, A291174.

Sequence in context: A348773 A130201 A076392 * A048373 A066563 A374085

Adjacent sequences: A291170 A291171 A291172 * A291174 A291175 A291176

Keyword

nonn,more

Author

Amiram Eldar, Aug 19 2017

Status

approved