13526
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 17
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 20292
- Proper Divisor Sum (Aliquot Sum)
- 6766
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 6762
- Möbius Function
- 1
- Radical
- 13526
- Omega Function (Ω)
- 2
- Little Omega Function (ω)
- 2
Special
- Factorial
- no
- Catalan Number
- no
- Bell Number
- no
- Motzkin Number
- no
- Primorial
- no
Figurate Numbers
- Fibonacci Number
- no
- Triangular Number
- no
- Perfect Square
- no
- Perfect Cube
- no
- Pentagonal Number
- no
- Hexagonal Number
- no
- Lucas Number
- no
- Tetrahedral Number
- no
- Pell Number
- no
- Tribonacci Number
- no
- Pronic Number
- no
Recreational
- Happy Number
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 37
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- Squarefree Number
- yes
- Prime Power
- no
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- yes
- Odd
- no
Appears in sequences
- Floor((e/2)^n).at n=31A014213
- a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n+1-k), where k = [ (n+1)/2 ], s = (Lucas numbers), t = (odd natural numbers).at n=21A024473
- a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n-k+1), where k = [ n/2 ], s = (Lucas numbers), t = (odd natural numbers).at n=20A025093
- a(n) = a(n-1) + a(n-2) + 4, with a(0)=0, a(1)=2.at n=17A168193
- Numbers n such that sigma(sigma(phi(n))) = sigma(sigma(n)).at n=23A172466
- a(n) = Sum_{k=0..n} binomial(n,k)*floor(sqrt(Bell(k)))*floor(sqrt(Bell(n-k))).at n=9A192574
- Half the number of nX2 0..3 arrays with no element equal to the average of its horizontal and vertical neighbors.at n=3A197103
- Half the number of nX4 0..3 arrays with no element equal to the average of its horizontal and vertical neighbors.at n=1A197105
- T(n,k)=Half the number of nXk 0..3 arrays with no element equal to the average of its horizontal and vertical neighbors.at n=11A197109
- T(n,k)=Half the number of nXk 0..3 arrays with no element equal to the average of its horizontal and vertical neighbors.at n=13A197109
- Number of 2 X 2 matrices with all elements in {0,1,...,n} and determinant in {0,1}.at n=38A209991
- Row sums of triangle in A204026.at n=33A238374
- Number of distinct linear polynomials b+c*x in row n of array generated as in Comments.at n=17A242448
- Limit of the coefficient of x^(3^m + n) in B(x)^(n+1)/(n+1) as m grows, where B(x) = Sum_{k>=0} x^(3^k).at n=9A277041
- a(1)=2, a(2)=3; then a(n+1) = smallest k such that S(k) = S(a(n)) + S(a(n-1)), (n>=2), where S is sopfr (A001414).at n=17A330988
- (A331763(n) - A331755(n+1))/2.at n=26A335687
- Nonprime numbers k whose arithmetic derivative k' (A003415) is a Fibonacci number (A000045).at n=34A362141
- Semiprimes k such that none of k-2, k-1, k+1, and k+2 is squarefree.at n=43A364010