15115
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 13
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 18144
- Proper Divisor Sum (Aliquot Sum)
- 3029
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 12088
- Möbius Function
- 1
- Radical
- 15115
- 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
- 89
- Smith Number
- yes
- 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
- no
- Odd
- yes
Appears in sequences
- Number of directed animals of size n (k=1 column of A038622); number of (s(0), s(1), ..., s(n)) such that s(i) is a nonnegative integer and |s(i) - s(i-1)| <= 1 for i = 1,2,...,n, where s(0) = 2; also sum of row n+1 of array T in A026323.at n=10A005774
- Triangular array that counts rooted polyominoes.at n=56A038622
- Number of partitions satisfying cn(1,5) < cn(0,5) + cn(2,5) + cn(3,5) and cn(4,5) < cn(0,5) + cn(2,5) + cn(3,5).at n=38A039872
- Triangle, read by rows, of pairwise sums of trinomial coefficients (A027907).at n=59A104029
- Riordan array (1/sqrt(1-2*x-3*x^2), M(x)-1) where M(x) is the g.f. of the Motzkin numbers A001006.at n=56A114422
- Triangle whose k-th column has e.g.f. exp(x)*sum{j=0..k, Bessel_I(k+j,2x)}.at n=56A116401
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, 1, -1), (1, -1, 0), (1, 0, -1), (1, 1, 1)}.at n=8A149588
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, 0, 1), (0, 1, -1), (1, 0, 1), (1, 1, 1)}.at n=7A150970
- Numbers n such that 15*prime(n)+{-4,-2,2,4} are all primes.at n=37A176002
- A binomial conjugate of the Narayana numbers.at n=56A177896
- Convolution of Lucas numbers and positive integers repeated (A000032 and A008619).at n=17A213046
- Start with a single hexagon; at n-th generation add a hexagon at each expandable vertex (this is the "vertex to side" version); a(n) is the sum of all label values at n-th generation. (See comment for construction rules.)at n=17A247905
- Numbers using only digits 1 and 5.at n=39A276037
- Semiprime numbers whose digit string can be partitioned into three parts such that the product of the first two parts equals the third part.at n=32A280636
- Value of the n-th Roman number interpreted as Latin alphabetic number.at n=6A285511
- Number of compositions of n whose non-adjacent parts are strictly decreasing.at n=37A333193
- Concatenations x||1||x for numbers x.at n=14A392225