Jyrki Lahtonen
Reputation
78,220
97/100 score
8 114 222
Impact
~1.0m people reached

 123 The limit of truncated sums of harmonic series, $\lim\limits_{k\to\infty}\sum_{n=k+1}^{2k}{\frac{1}{n}}$ 54 How do we prove $n^n \mid m^m \Rightarrow n \mid m$? 50 Are there any irrational numbers that have a difference of a rational number? 44 An example of a division ring $D$ that is **not** isomorphic to its opposite ring 43 Is $\sqrt1+\sqrt2+\dots+\sqrt n$ ever an integer?

### Reputation (78,220)

 +175 Expansion of $(1+\sqrt{2})^n$ +10 Express roots in polynomials of equation $x^3+x^2-2x-1=0$ +8 If $G$ is a non-abelian group of order 10, prove that $G$ has five elements of order 2. +10 Irrational P-adics

### Questions (9)

 26 On the norm of a quotient of a Banach space. 16 Is it possible for an irreducible polynomial with rational coefficients to have three zeros in an arithmetic progression? 14 Connected unbounded sets $S\subset \Bbb{R}^n$ such that $x\mapsto ||x||^t$ is uniformly continuous on $S$? 13 Is there a group homomorphism $\Bbb{C}^*\to\Bbb{R}^*$ with a countable kernel? 12 Will this sequence of polynomials converge to a Hermite polynomial pointwise?

### Tags (378)

 2k abstract-algebra × 504 566 number-theory × 161 811 group-theory × 228 554 elementary-number-theory × 160 796 finite-fields × 347 511 galois-theory × 185 668 field-theory × 225 511 polynomials × 159 600 linear-algebra × 201 359 finite-groups × 95

### Accounts (23)

 Mathematics♦ 78,220 rep 8114222 MathOverflow 1,007 rep 611 Mathematics Educators 910 rep 314 Academia 320 rep 16 TeX - LaTeX 277 rep 212

 +100 Fraction field of $p$-adic power series ring