15836
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 23
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 28728
- Proper Divisor Sum (Aliquot Sum)
- 12892
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 7632
- Möbius Function
- 0
- Radical
- 7918
- Omega Function (Ω)
- 4
- Little Omega Function (ω)
- 3
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
- 146
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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
- Number of partitions of n that do not contain 2 as a part.at n=42A027336
- Number of polydudes(1): a(n) is the number of polydudes with n cells. See the first link for the source of this sequence. The definition is unknown. Not the same as A091130.at n=10A056843
- a(n) = 2^n mod Fibonacci(n).at n=28A057862
- A Wallis pair (x,y) satisfies sigma(x^2) = sigma(y^2); sequence gives y's for indecomposable Wallis pairs with x < y (ordered by values of x).at n=37A075769
- Sum of the first n twin prime pairs.at n=29A086169
- Even numbers n such that 37^2 (the square of the first irregular prime) divides the numerator of Bernoulli(n).at n=28A090789
- Number of partitions of n-th composite number not containing the smallest prime factor.at n=27A091094
- Integer part of the area of circles with prime radii.at n=19A097427
- a(n) = A002865(2*n-1)+A002865(2*n).at n=20A182845
- Number of 3-step left-handed knight's tours (moves only out two, left one) on an n X n board summed over all starting positions.at n=38A187173
- Increasing sequence generated by these rules: a(1)=1, and if x is in a then 3x-1 and x^2 are in a.at n=59A191289
- Numbers which, when divided by the sum of their prime factors, give a prime number.at n=43A199013
- Number of -n..n arrays x(0..3) of 4 elements with zero sum and nonzero second differences.at n=13A200554
- Number of partitions of n with the property that if two summands have the same parity, then their frequencies have the same parity.at n=42A240949
- Indices of primes in A000712.at n=20A285217
- Take apart the sides of each of the integer-sided triangles with perimeter n (at their vertices) and rearrange them orthogonally in 3-space so that their endpoints coincide at a single point. a(n) is the total volume of all rectangular prisms enclosed in this way.at n=29A308233
- Number of even parts in the partitions of n into 8 parts.at n=42A309630
- Number of Dyck bridges with resets to zero from (0,0) to (n,0).at n=13A369316
- G.f. satisfies A(x) = 1/(1-x)^4 + x^4*A(x)^4.at n=9A369693
- a(n) = Sum_{k=0..n} (k+1) * binomial(2*k,2*n-2*k).at n=9A381421