15018
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 30048
- Proper Divisor Sum (Aliquot Sum)
- 15030
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- yes
Derived Values
- Euler's Totient
- 5004
- Möbius Function
- -1
- Radical
- 15018
- Omega Function (Ω)
- 3
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 27
- Smith Number
- yes
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- 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
- Number of rooted genus-2 maps with n edges.at n=2A006299
- Expansion of (1+x-x^3)/((1-2*x)*(1-x^2)).at n=13A052997
- Numbers which are the sum of their proper divisors containing the digit 5.at n=17A059464
- Sum of squared factorials: (0!)^2 + (1!)^2 + (2!)^2 + (3!)^2 +...+ (n!)^2.at n=5A061062
- Total number of parts in all partitions of n into odd parts.at n=41A067588
- a(n) = A135574(3*n) + A135574(3*n+1) + A135574(3*n+2).at n=4A137223
- a(0)=a(1)=1. For n >= 2, if a(n-1) is coprime to n, then a(n) = a(n-1) + a(n-2). Otherwise, a(n)=1.at n=43A139047
- Inverse binomial transform of A020806.at n=13A144471
- 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, 0, 1), (0, 1, -1), (1, -1, 1), (1, 0, 1), (1, 1, 0)}.at n=7A150876
- Number of binary strings of length 2n which contain the reversals of each of their two halves.at n=9A237501
- Positive integers m such that pi(m^2) = pi(j^2) + pi(k^2) for no 0 < j <= k < m.at n=47A262408
- Triangle read by rows: T(n,f) is the number of rooted maps with n edges and f faces on an orientable surface of genus 2.at n=4A269922
- Triangle read by rows: T(n,g) is the number of rooted maps with n edges and 2 faces on an orientable surface of genus g.at n=11A270406
- Decimal representation of the x-axis, from the left edge to the origin, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 14", based on the 5-celled von Neumann neighborhood.at n=13A277954
- Decimal representation of the x-axis, from the left edge to the origin, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 841", based on the 5-celled von Neumann neighborhood.at n=14A284245
- a(n) is the number of rooted maps with n edges and 2 faces on an orientable surface of genus 2.at n=1A288082
- Number of nX6 0..1 arrays with every element equal to 0, 3, 4, 5 or 8 king-move adjacent elements, with upper left element zero.at n=7A298780
- a(n) = Sum_{k=1..n} k^2*tau(k), where tau is A000005.at n=21A319085
- a(n) = (11*2^n - 2*(-1)^n)/3 for n >= 0.at n=12A340627