13265
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 17
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 18240
- Proper Divisor Sum (Aliquot Sum)
- 4975
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 9072
- Möbius Function
- -1
- Radical
- 13265
- 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
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 76
- Smith Number
- no
- 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
- no
- Odd
- yes
Appears in sequences
- Start with 1, apply 1->12, 21->21, 22->21, 2->2 (for final 2); a(n) = length of n-th term.at n=29A013950
- Expansion of x^2*(2 - x + x^2) / ((1 + x)*(1 - x)^4).at n=41A026035
- Number of self-avoiding polygons with perimeter n on hexagonal [ =triangular ] lattice.at n=11A036418
- Number of ordered factorizations with 3 levels of parentheses indexed by prime signatures: A050358(A025487(n)).at n=19A050359
- Thickened pyramidal numbers: a(n) = 2*(n+1)*n + Sum_{i=1..n} (4*i*(i-1) + 1).at n=21A050533
- Number of 2 X 2 singular integer matrices with elements from {0,...,n}.at n=40A059306
- Numbers k such that the smoothly undulating palindromic number (75*10^k - 57)/99 is a prime.at n=9A062224
- Pascal-(1,7,1) array.at n=48A081582
- Pascal-(1,7,1) array.at n=51A081582
- a(1)=1, a(n)=a(n-1)+n^0 if n odd, a(n)=a(n-1)+ n^2 if n is even.at n=41A135301
- Duplicate of A081582.at n=48A143681
- a(n) equals the sum of path counts in the (right-aligned Ferrers plots of) the partitions of n.at n=20A180684
- Smallest k such that 6^n+k, 6^n+k+g, 6^n+k+2*g are consecutive primes in arithmetic progression.at n=40A233546
- Sum over all Dyck paths of semilength n of products over all peaks p of y_p, where y_p is the y-coordinate of peak p.at n=7A258173
- Expansion of Product_{k>=0} 1/(1-x^(4*k+1))^(4*k+1).at n=33A285048
- Number of matching pairs of patterns, the first of length n and the second of length k.at n=23A335518
- First member of the Diophantine pair (m, k) that satisfies 8*(m^2 + m) = k^2 + k; a(n) = m.at n=6A336623
- Numbers m such that d(1)^0 + d(2)^1 + ... + d(k)^(k-1) = d(1)! + d(2)! + ... + d(k)!, where d(i), i=1..k, are the digits of m.at n=41A342944
- Array read by downward antidiagonals: A(n,k) = A(n-1,k+1) + (k+1)*Sum_{j=0..k} A(n-1,j) with A(0,k) = k+1, n >= 0, k >= 0.at n=27A371567
- Expansion of e.g.f. -LambertW(-x / (1 - 2*x)).at n=5A376100