Those Fascinating Numbers 143
2 137
the smallest number n requiring nine iterations of the σI (n) function in order
to reach 1 (see the number 193).
2 158
the second solution of σ2(n) = σ2(n + 4) (see the number 430).
2 176 (=
27
· 17)
the 14th unitary hyperperfect number (see the number 288).
2 178
the second number which is not a palindrome but which divides the number
obtained by reversing its digits (see the number 1 089).
2 184
the smallest number n such that each of the numbers n + i, i = 0, 1, 2, . . . , 16,
has a factor in common with the product of the other 16 (R.K. Guy [101], B28,
with an obvious error in the formulation): the sequence of numbers satisfying
this property begins as follows: 2 184, 27 830, 32 214, 57 860, 62 244, 87 890,
92 274, . . .
2 187
possibly the largest 3-powerful number which is the nearest (a distance of 10) to
the following 3-powerful number, namely 2197: here 2 187 =
37
and 2 197 =
133;
the next relatively small gap (this one being equal to 28) occurs with the
numbers 50 625 =
34
·
54
and 50 653 =
273.
2 203
the exponent of the 16th Mersenne prime 22 203 1 (Robinson, 1952).
2 204
the
11th
solution of φ(n) = φ(n + 1) (see the number 15).
2 205
the third of the existing eight primitive non deficient numbers (see the number
945).
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