Properties of the Number 31520

Thirty-One Thousand Five Hundred Twenty

Basics

Value: 31519 → 31520 → 31521

Parity: even

Prime: No

Previous Prime: 31517

Next Prime: 31531

Digit Sum: 11

Digital Root: 2

Palindrome: No

Factorization: 2 ⁵ × 5 × 197

Divisors: 1, 2, 4, 5, 8, 10, 16, 20, 32, 40

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 111101100100000

Octal: 75440

Duodecimal: 162A8

Hexadecimal: 7b20

Square: 993510400

Square Root: 177.53872816937718

Classification

Fibonacci: No

Bell Number: No

Factorial Number: No

Regular Number: No

Perfect Number: No

Special

Kaprekar Constant: No

Munchausen Constant: No

Armstrong Number: No

Kaprekar Number: No

Catalan Number: No

Vampire Number: No

Taxicab Number: No

Super Prime: No

Friedman Number: No

Fermat Number: No

Cullen Number: No

OEIS Sequences

a(0) = 1, a(1) = 2, a(n) = 4·a(n-1) - 2·a(n-2), n >= 2. A6012

Expansion of g.f. (1 + x - 2·x² - x³)/(1 - 4·x² + 2·x⁴). A30436

Number T(n,k) of permutations p of [n] with no fixed points where the maximal displacement of an element equals k; triangle T(n,k), n>=0, 0<=k<=n, read by rows. A259784

T(n,k)=Number of (n+2)X(k+2) 0..3 arrays with every 3X3 subblock row and column sum not 2 4 5 or 7 and every diagonal and antidiagonal sum 2 4 5 or 7. A251876

a(0)=0; a(1)=1; a(n) = a(n-1) + (3 + (-1)ⁿ)*a(n-2)/2. A62112

a(n) = coefficient of·in (1+x)ⁿ mod (1+x⁴). A99587

G.f.: 1/(1 + x - x² - x³ + x⁴). A199803

Number of permutations of [n] with no fixed points where the maximal displacement of an element equals n-1. A259834

T(n,k) = ∑_i=0..k (-1)^k-i*binomial(k,i)*A000670(n-k+i). A122101

G.f.: 1/(1-2·x+2·x²-x³+x⁴). A199802