15124
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
- 2
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 28000
- Proper Divisor Sum (Aliquot Sum)
- 12876
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 7128
- Möbius Function
- 0
- Radical
- 7562
- 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
- 40
- 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
- a(n) = 8*a(n-1) - a(n-2); a(0) = 1, a(1) = 4.at n=5A001091
- Number of strict (-1)st-order maximal independent sets in cycle graph.at n=19A007390
- Base-7 Armstrong or narcissistic numbers, written in base 7.at n=18A010349
- a(n) = 5th Chebyshev polynomial (first kind) evaluated at 2^n.at n=2A020539
- a(n) = Lucas(n+2) - 3.at n=17A027961
- Numbers k such that 163*2^k+1 is prime.at n=37A032458
- Numerators of continued fraction convergents to sqrt(15).at n=9A041022
- Numerators of continued fraction convergents to sqrt(375).at n=9A041710
- a(n)*a(n+3) - a(n+1)*a(n+2) = 3, given a(0)=a(1)=1, a(2)=4.at n=10A080871
- a(n) = Lucas(4n) - 3, or Lucas(2n-1)*Lucas(2n+1).at n=4A081078
- Number triangle associated to Chebyshev polynomials of first kind.at n=49A101124
- A determinant sum sequence of the D3 dihehral 2 X 2 representation.at n=9A120496
- Denominators in continued fraction expansion of sqrt(3/5).at n=9A145543
- a(n) = 4*(5*n^2 - 5*n + 1).at n=27A193448
- Numbers k such that at least one other integer m exists with the same smallest and same largest prime factors, and same multisets of decimal and binary digits as k.at n=37A214621
- G.f.: 1 / G(0), where G(k) = 1 - q^(k+1) / (1 - q^(k+1)/G(k+2) ).at n=14A226729
- Number of 1's in A132199 preceding the n-th Rowland prime, A137613(n).at n=36A226781
- a(n) = gcd(Sum_{k=1...n} L(k), Product_{j=1...n} L(j)), where L(k) is the k-th Lucas number.at n=17A239799
- a(n) = 16*n^5 - 20*n^3 + 5*n.at n=4A243131
- Number of length-n 0..5 arrays with no repeated value equal to the previous repeated value, with new values introduced in sequential order.at n=8A268953