Below or above

Katılım
19 Ekim 2007
Mesajlar
2
Excel Vers. ve Dili
İngilizce
It asks "find how many numbers are strictly below than 2000".
If it says "strictly", don't we count 2000?
 
Katılım
25 Aralık 2005
Mesajlar
4,160
Excel Vers. ve Dili
MS Office 2010 Pro Türkçe
A strictly non-palindromic number is an integer n that is not palindromic in any numeral system with a base b in the range 2 ≤ b ≤ n − 2. For example, the number six is written as 110 in base 2, 20 in base 3 and 12 in base 4, none of which is a palindrome—so 6 is strictly non-palindromic.

The sequence of strictly non-palindromic numbers starts:

1, 2, 3, 4, 6, 11, 19, 47, 53, 79, 103, 137, 139, 149, 163, 167, 179, 223, 263, 269, 283, 293, …

To test whether a number n is strictly non-palindromic, it must be verified that n is non-palindromic in all bases up to n − 2. The reasons for this upper limit are:
any n ≥ 3 is written 11 in base n − 1, so n is palindromic in base n − 1;
any n ≥ 2 is written 10 in base n, so any n is non-palindromic in base n;
any n ≥ 1 is a single-digit number in any base b > n, so any n is palindromic in all such bases.
Thus it can be seen that the upper limit of n − 2 is necessary to obtain a mathematically 'interesting' definition.
For n < 4 the range of bases is empty, so these numbers are strictly non-palindromic in a trivial way.

Strictly non-palindromic numbers: n is not palindromic in any base b with 2 <= b <= n-2.

1, 2, 3, 4, 6, 11, 19, 47, 53, 79, 103, 137, 139, 149, 163, 167, 179, 223, 263, 269, 283, 293, 311, 317, 347, 359, 367, 389, 439, 491, 563, 569, 593, 607, 659, 739, 827, 853, 877, 977, 983, 997, 1019, 1049, 1061, 1187, 1213, 1237, 1367, 1433, 1439, 1447, 1459
 
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Katılım
7 Temmuz 2004
Mesajlar
12,406
Excel Vers. ve Dili
64 Bit 2010 - İngilizce
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