Use precisely four 9's, and build an expression that works out to 161.
(I) At least one 9 can be turned upside down to 6.
(II) None of the 9s can be turned around to 6.
(In reply to
One more by Ady TZIDON)
The prepended exclamation mark apparently means
<table width="100%" cellspacing="0" cellpadding="0" border="0" style="font-family: "Times New Roman"; background-color: rgb(238, 238, 255);"><tbody><tr><td valign="top" align="left" width="100">
A000166</td><td width="5"></td><td valign="top" align="left">
Subfactorial or rencontres numbers, or derangements: number of permutations of n elements with no fixed points.</td></tr></tbody></table>
though the OEIS in its notes does not mention this notation. The way I found its meaning was by typing !2, !3, !4, !5, !6 into Wolfram Alpha and entering the resulting numbers into OEIS.
|
|
Posted by Charlie
on 2023-09-27 09:57:05 |
re: One more
