Problems
| ID | Description / Title | Solved By |
|---|---|---|
401 | Sum of squares of divisors | |
402 | Integer-valued polynomials | |
403 | Lattice points enclosed by parabola and line | |
404 | Crisscross Ellipses | |
405 | A rectangular tiling | |
406 | Guessing Game | |
407 | Idempotents | |
408 | Admissible paths through a grid | |
409 | Nim Extreme | |
410 | Circle and tangent line | |
411 | Uphill paths | |
412 | Gnomon numbering | |
413 | One-child Numbers | |
414 | Kaprekar constant | |
415 | Titanic sets | |
416 | A frog's trip | |
417 | Reciprocal cycles II | |
418 | Factorisation triples | |
419 | Look and say sequence | |
420 | 2x2 positive integer matrix | |
421 | Prime factors of n15+1 | |
422 | Sequence of points on a hyperbola | |
423 | Consecutive die throws | |
424 | Kakuro | |
425 | Prime connection | |
426 | Box-ball system | |
427 | n-sequences | |
428 | Necklace of circles |