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Problems Archives

The problems archives table shows problems 1 to 751. If you would like to tackle the 10 most recently published problems then go to Recent problems.
Click the description/title of the problem to view details and submit your answer.


ID

Description / TitleSolved By
501Eight Divisors
1232
502Counting Castles
262
503Compromise or persist
290
504Square on the Inside
2887
505Bidirectional Recurrence
195
506Clock sequence
817
507Shortest Lattice Vector
198
508Integers in base i-1
213
509Divisor Nim
523
510Tangent Circles
950
511Sequences with nice divisibility properties
380
512Sums of totients of powers
1405
513Integral median
288
514Geoboard Shapes
199
515Dissonant Numbers
434
5165-smooth totients
1462
517A real recursion
428
518Prime triples and geometric sequences
1502
519Tricoloured Coin Fountains
319
520Simbers
375
521Smallest prime factor
687
522Hilbert's Blackout
247
523First Sort I
910
524First Sort II
199
525Rolling Ellipse
457
526Largest prime factors of consecutive numbers
280
527Randomized Binary Search
677
528Constrained Sums
253
52910-substrings
224
530GCD of Divisors
417
531Chinese leftovers
1048
532Nanobots on Geodesics
285
533Minimum values of the Carmichael function
299
534Weak Queens
271
535Fractal Sequence
265
536Modulo power identity
262
537Counting tuples
565
538Maximum quadrilaterals
301
539Odd elimination
758
540Counting primitive Pythagorean triples
587
541Divisibility of Harmonic Number Denominators
191
542Geometric Progression with Maximum Sum
214
543Prime-Sum Numbers
640
544Chromatic Conundrum
219
545Faulhaber's Formulas
485
546The Floor's Revenge
211
547Distance of random points within hollow square laminae
197
548Gozinta Chains
562
549Divisibility of factorials
2532
550Divisor game
313