login
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).
1
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).
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
KEYWORD
nonn,more
AUTHOR
Amiram Eldar, Aug 19 2017
STATUS
approved