Saturday, November 12, 2016

Number of the day: 8889

Properties of the number 8889:

8889 = 3 × 2963 is semiprime and squarefree.
8889 has 2 distinct prime factors, 4 divisors, 7 antidivisors and 5924 totatives.
8889 has a semiprime digit sum 33 in base 10.
8889 = (22 × 23)/2 + … + (39 × 40)/2 is the sum of at least 2 consecutive triangular numbers in 1 way.
8889 = 44452 - 44442 = 14832 - 14802 is the difference of 2 nonnegative squares in 2 ways.
8889 is the sum of 2 positive triangular numbers.
8889 is the difference of 2 positive pentagonal numbers in 1 way.
8889 = 22 + 72 + 942 is the sum of 3 positive squares.
88892 is the sum of 3 positive squares.
8889 is a divisor of 131481 - 1.
8889 is an emirpimes in (at least) the following bases: 9, 11, 12, 15, 18, 20, 23, 29, 34, 60, 63, 72, 77, 81, 84, 86, 87, 90, 95, and 99.
8889 is palindromic in (at least) the following bases: 25, 30, and 88.
8889 consists of only the digits '8' and '9'.
8889 in base 25 = e5e and consists of only the digits '5' and 'e'.
8889 in base 30 = 9q9 and consists of only the digits '9' and 'q'.

The number 8889 belongs to the following On-Line Encyclopedia of Integer Sequences (OEIS) sequences (among others):

Sequence numbers and descriptions below are taken from OEIS.
A057534: a(n+1) = a(n)/2 if 2|a(n), a(n)/3 if 3|a(n), a(n)/5 if 5|a(n), a(n)/7 if 7|a(n), a(n)/11 if 11|a(n), a(n)/13 if 13|a(n), else 17*a(n)+1.
A059482: a(0)=1, a(n) = a(n-1) + 8*10^(n-1).
A080961: Fourth binomial transform of A010686 (period 2: repeat 1,5).
A125082: a(n) = n^4-n^3-n^2-n-1.
A178325: G.f.: A(x) = Sum_{n>=0} x^n/(1-x)^(n^2).
A178369: Numbers with rounded up arithmetic mean of digits = 9.
A213580: Principal diagonal of the convolution array A213579.
A220127: Number of tilings of a 10 X n rectangle using integer sided rectangular tiles of area 10.
A237346: For k in {2,3,...,9} define a sequence as follows: a(0)=0; for n>=0, a(n+1)=a(n)+1, unless a(n) ends in k, in which case a(n+1) is obtained by replacing the last digit of a(n) by the digit(s) of k^2. This is k(9).
A256341: Numbers which have only digits 8 and 9 in base 10.

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