246 Jean-Marie De Koninck
188 355
the second number which is not the square of a prime number, but which
can be written as the sum of the squares of some of its prime factors: here
188 355 = 3 · 5 · 29 · 433 =
52
+
292
+
4332
(see the number 870).
189 375
the first of the smallest eight consecutive numbers at which the Ω(n) function
takes distinct values, namely here the values 6, 8, 1, 7, 3, 5, 2 and 4 (see the
number 726).
194 979
the largest number which can be written as the sum of the fifth powers of its
digits: 194 979 =
15
+
95
+
45
+
95
+
75
+
95
(see the number 4 150).
195 556
the only composite number n 109 such that σ(n + 10) = σ(n) + 10.
197 210
the second number which can be written as the sum of the squares of two prime
numbers in 5 distinct ways (as well as 6 and 7): 197 210 =
312
+
4432
=
672
+
4392
=
1072
+
4312
=
1732
+
4092
=
1992
+
3972
=
2412
+
3732
=
3112
+
3172
(see the number 338).
199 584
the second solution of
σ(n)
n
=
11
3
(see the number 35 640).
199 606
the seventh number n such that 2n −2 (mod n) (see the number 946).
203 391
the smallest number n such that n and n + 1 each have nine prime factors
(counting their multiplicity); indeed, 203 391 =
38
· 31 and 203 392 =
27
· 7 · 227
(see the number 135).
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