15019
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 16
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 15696
- Proper Divisor Sum (Aliquot Sum)
- 677
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 14344
- Möbius Function
- 1
- Radical
- 15019
- 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
- 133
- 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
- no
- Odd
- yes
Appears in sequences
- a(n) = 1*t(n) + 2*t(n-1) + ... + k*t(n+1-k), where k=floor((n+1)/2) and t = A008578 ({1} U primes).at n=35A023862
- a(n) = 1*prime(n) + 2*prime(n-1) + ... + k*prime(n+1-k), where k=floor((n+1)/2) and prime(n) is the n-th prime.at n=34A023870
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 64 ones.at n=34A031832
- Numbers k such that 117*2^k+1 is prime.at n=21A032408
- Trajectory of 1 under map n->49n+1 if n odd, n->n/2 if n even.at n=6A033980
- Number of compositions of n into nonprime numbers.at n=25A052284
- Number of planar partitions of n with exactly 3 rows.at n=17A091357
- Records in A109890.at n=19A111242
- a(n) = a(n-1) + 4*a(n-2) - 4*a(n-3) for n>3.at n=14A136336
- a(n) = 5*a(n-1) - 9*a(n-2) + 8*a(n-3) - 4*a(n-4), with a(0)=0, a(1)=0, a(2)=0, a(3)=1.at n=13A137221
- 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=45A139047
- Dispersion of A004767 (4k+3, k>=0), by antidiagonals.at n=38A191669
- a(n) = (11*4^n + 1)/3.at n=6A199210
- Palindromic numbers in bases 4 and 8 written in base 10.at n=39A259382
- Number of length-n ternary sequences where the sum of each block differs by at most 1 from every other block of the same length.at n=41A274008
- Decimal representation of the x-axis, from the origin to the right edge, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 366", based on the 5-celled von Neumann neighborhood.at n=14A281421
- Number of pairs (lambda,mu) of partitions lambda of n and mu of nine with mu <= lambda (by diagram containment).at n=12A303859
- Number of multiset partitions of strongly normal multisets of size n such that the blocks have empty intersection.at n=7A317755
- Row 2 of A328464: a(n) = A276156(4n - 2) / 2.at n=17A328465
- a(1) = 1; a(n) = Sum_{k=1..ceiling(n/2)} a(k) * a(n-k).at n=13A348530