A290146 Records of the maxima of the unitary aliquot sequences of the numbers in A290145.

54, 90, 126, 162, 198, 378, 4950, 12978, 82278, 94218606, 8855754260391450, 645856907610421353834, 1350253136232108126126, 27709820863862780667438

Offset

1,1

Links

Table of n, a(n) for n=1..14.

Example

The unitary aliquot sequence of 174 is: 174, 186, 198, 162, 84, 76, 24, 12, 8, 1. Its maximum is 198 which larger than the maxima of all the aliquot sequences of the numbers below 174.

Mathematica

usigma[n_] := If[n == 1, 1, Times @@ (1 + Power @@@ FactorInteger[n])];
g[n_] := If[n > 0, usigma[n] - n, 0]; f[n_] := NestWhileList[g, n, UnsameQ, All]; a = -1; rec = {}; Do[b = Length[f[n]] - 2; If[b > a, a = b; AppendTo[rec, b ]], {n, 10^6}] ; rec (* after Giovanni Resta at A034448 & Robert G. Wilson v at A098009 *)

Crossrefs

Cf. A098008, A098009, A098010, A290145.

Sequence in context: A180150 A096512 A243542 * A071863 A045933 A088986

Adjacent sequences: A290143 A290144 A290145 * A290147 A290148 A290149

Keyword

nonn,more

Author

Amiram Eldar, Jul 21 2017

Status

approved