Tuesday, November 15, 2016

Number of the day: 7230

Properties of the number 7230:

7230 = 2 × 3 × 5 × 241 is the 6305th composite number and is squarefree.
7230 has 4 distinct prime factors, 16 divisors, 9 antidivisors and 1920 totatives.
7230 has an oblong digit sum 12 in base 10.
7230 = 412 + … + 442 = 362 + … + 402 is the sum of at least 2 consecutive positive squares in 2 ways.
7230 is the sum of 2 positive triangular numbers.
7230 is the difference of 2 positive pentagonal numbers in 2 ways.
7230 = 12 + 22 + 852 is the sum of 3 positive squares.
72302 = 36002 + 62702 = 8822 + 71762 = 28562 + 66422 = 43382 + 57842 is the sum of 2 positive squares in 4 ways.
72302 is the sum of 3 positive squares.
7230 is a divisor of 6594 - 1.
7230 = '72' + '30' is the concatenation of 2 oblong numbers.
7230 is palindromic in (at least) the following bases: 22, 31, 52, and -29.
7230 in base 15 = 2220 and consists of only the digits '0' and '2'.
7230 in base 22 = eke and consists of only the digits 'e' and 'k'.
7230 in base 28 = 966 and consists of only the digits '6' and '9'.
7230 in base 31 = 7g7 and consists of only the digits '7' and 'g'.
7230 in base 42 = 446 and consists of only the digits '4' and '6'.
7230 in base 51 = 2dd and consists of only the digits '2' and 'd'.
7230 in base 52 = 2Z2 and consists of only the digits '2' and 'Z'.

The number 7230 belongs to the following On-Line Encyclopedia of Integer Sequences (OEIS) sequences (among others):

Sequence numbers and descriptions below are taken from OEIS.
A027575: a(n) = n^2 + (n+1)^2 + (n+2)^2 + (n+3)^2.
A027578: Sums of five consecutive squares: a(n) = n^2 + (n+1)^2 + (n+2)^2 + (n+3)^2 + (n+4)^2.
A031712: Least term in period of continued fraction for sqrt(n) is 34.
A059255: Both sum of n+1 consecutive squares and sum of the immediately following n consecutive squares.
A062681: Numbers that are sums of 2 or more consecutive squares in more than 1 way.
A062693: Squarefree n such that the elliptic curve n*y^2 = x^3 - x arising in the "congruent number" problem has rank 3.
A110064: a(n+4) = a(n+1) - a(n), a(0) = 1, a(1) = -4, a(2) = 0, a(3) = 1.
A139275: a(n) = n*(8*n+1).
A229272: Numbers n for which n' + n and n' - n are both prime, n' being the arithmetic derivative of n.
A253805: a(n) gives one fourth of the even leg of the second of the two Pythagorean triangles with hypothenuse A080109(n) = A002144(n)^2. The odd leg is given in A253804(n).

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