15808
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 22
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 28
- Divisor Sum
- 35560
- Proper Divisor Sum (Aliquot Sum)
- 19752
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 6912
- Möbius Function
- 0
- Radical
- 494
- Omega Function (Ω)
- 8
- 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
- 53
- 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
- tan(sinh(x)*arcsin(x))=2/2!*x^2+8/4!*x^4+320/6!*x^6+15808/8!*x^8...at n=4A012536
- arctanh(sinh(x)*arcsin(x))=2/2!*x^2+8/4!*x^4+320/6!*x^6+15808/8!*x^8...at n=4A012541
- T(2n+4,n), array T as in A055794.at n=11A055797
- Triangle of Stirling numbers of order 4.at n=22A059023
- 1 + Sum_{n >= 1} Sum_{k = 0..n-1} (-1)^n*T(n,k)*y^(2*k)*x^(2*n)/(2*n)! = JacobiCN(x,y).at n=13A060627
- Number of binary bit strings of length n with no block of 8 or more 0's. Nonzero heptanacci numbers, A122189.at n=15A066178
- Sum of remainders when n-th Fibonacci number is divided by all smaller Fibonacci numbers > 1.at n=21A072523
- Triangle read by rows: T(n,k) = number of peakless Motzkin paths of length n containing k UHH...HD's, where U=(1,1), D=(1,-1) and H=(1,0) (can be easily expressed using RNA secondary structure terminology).at n=54A089741
- Triangle read by rows: T(n,k) is the number of Dyck paths of semilength n having pyramid weight k.at n=75A091866
- Triangle read by rows: T(n,k) is the number of Dyck paths of semilength n having k exterior pairs.at n=49A091977
- Triangle read by rows: number of Motzkin paths by length and by number of humps.at n=51A097229
- Lower triangular matrix T, read by rows, such that T(n,0) = 1 and T(n,k) = T(n-1,k) + T^2(n-1,k-1) for k>0, where T^2 is the matrix square of T.at n=42A097712
- Triangle read by rows: T(n,k) is the number of Motzkin paths of length n having k high humps. (A hump is an upstep followed by 0 or more flatsteps followed by a downstep. A high hump is a hump that starts at a level higher than zero.).at n=40A097888
- Half the number of permutations of 0..n with exactly two maxima.at n=8A100575
- Expansion of (-1+x^3+x^6+x^9)/((1-x)*(2*x-1)*(x^2+1)*(x^2+x+1)*(x^4-x^2+1)).at n=14A111663
- Heptanacci numbers: each term is the sum of the preceding 7 terms, with a(0),...,a(6) = 0,0,0,0,0,0,1.at n=21A122189
- Triangle T(n, k) = 2^(k-1) * E(n, k-1) where E(n,k) are the Eulerian numbers A173018, read by rows.at n=34A142075
- 8 times octagonal numbers: 8*n*(3*n-2).at n=26A153808
- T(n, k) = E(n, k)*2^k where E(n,k) are the Eulerian numbers A173018, for n > 0 and 0 <= k <= n-1, additionally T(0,0) = 1.at n=35A156365
- If an array is made of columns of -nacci sequences, fibo-, tribo- etc. all starting w. 1,1,2 etc, the NW to SE diagonals can be extended by computation. The above is diagonal 10. See A159741 for details.at n=5A159747