cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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).

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%I A291173 #9 Aug 31 2017 17:43:38
%S A291173 2,42,90,210,630,1050,1470,2310,6930,16170,30030,90090,150150,210210,
%T A291173 570570,690690,870870,2072070,3573570,3993990,4834830
%N 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).
%C A291173 A variation of A286268 (Totient superabundant numbers).
%e A291173 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 A291173 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 A291173 Cf. A092693, A286268, A291174.
%K A291173 nonn,more
%O A291173 1,1
%A A291173 _Amiram Eldar_, Aug 19 2017