This was post by me on Maths SEMaths SE: but it did not get any solution.
Some months ago I made the following conjecture -
Let $d(n)$ denote the number of divisors of $n $.
Then let $N$ be a number such that $d(N)$ divides $N$ . Also let $I= \frac{N}{d(N)}$ which is defined as the "Index of Beauty of $N$ ".
Then, For every number $I$ there exists a number $N$ such that $I$ is the index of beauty of $N$.
This conjecture was proved false by Greg Martin herehere.
He said that it can be showed by exaustive computation that the following $I$ fail the conjecture under $1000$ are $\{18, 27, 30, 45, 63, 64, 72, 99, 105, 112, 117, 144, 153, 160, 162,
165, 171, 195, 207, 225, 243, 252, 255, 261, 279, 285, 288, 294, 320,
333, 336, 345, 352, 360, 369, 387, 396, 405, 416, 423, 435, 441, 465,
468, 477, 490, 504, 531, 544, 549, 555, 567, 576, 603, 608, 612, 615,
616, 625, 639, 645, 657, 684, 705, 711, 726, 728, 735, 736, 747, 792,
795, 801, 810, 828, 840, 873, 880, 885, 891, 909, 915, 927, 928, 936,
952, 960, 963, 981, 992\}$
Now what I am interested is that sequence of $I$ that fails.
(i) Is this sequence infinite?How?
(ii)Is there any approximation which can tell the number of such failed $I$ less than a fixed $x$
(iii)If the sequence is infinite then are there canonical forms in which all of the values are in our list.