Those Fascinating Numbers 327
275 305 224
the number of 5 × 5 magic squares, excluding rotations and reflections (see the
number 880).
275 890 944
the sixth solution of
σ(n)
n
=
10
3
(see the number 1 080).
282 977 280 (=
210
·
33
· 5 · 23 · 89)
the fourth solution of
σ(n)
n
=
15
4
(see the number 293 760).
283 417 216
the 20th dihedral perfect number (see the number 130).
292 965 218
the smallest number which can be written as the sum of three distinct fourth
powers in five and in six distinct ways:
292 965 218 =
24
+
1094
+
1114
=
214
+
984
+
1194
=
274
+
944
+
1214
=
344
+
894
+
1234
=
494
+
774
+
1264
=
614
+
664
+
1274
(see the number 6 578).
297 387 757
the first term of the smallest sequence of 17 consecutive prime numbers all of
the form 4n + 1 (see the number 2 593).
297 779 117
the first term of the smallest sequence of 18 consecutive prime numbers all of
the form 4n + 1 (see the number 2 593).
298 995 972
the third 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 298 995 972 =
22
· 3 · 11 · 131 · 17291 =
32
+
112
+
1312
+
172912
(see the number 870).
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