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Problems Archives

  • Problem 727 will be accessible in 8 hours, 45 minutes (Saturday, 26th September 2020, 11:00 pm)

The problems archives table shows problems 1 to 716. 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
1163
502Counting Castles
238
503Compromise or persist
276
504Square on the Inside
2759
505Bidirectional Recurrence
185
506Clock sequence
769
507Shortest Lattice Vector
184
508Integers in base i-1
204
509Divisor Nim
500
510Tangent Circles
905
511Sequences with nice divisibility properties
367
512Sums of totients of powers
1330
513Integral median
271
514Geoboard Shapes
190
515Dissonant Numbers
404
5165-smooth totients
1392
517A real recursion
411
518Prime triples and geometric sequences
1428
519Tricoloured Coin Fountains
307
520Simbers
352
521Smallest prime factor
660
522Hilbert's Blackout
229
523First Sort I
867
524First Sort II
185
525Rolling Ellipse
434
526Largest prime factors of consecutive numbers
268
527Randomized Binary Search
645
528Constrained Sums
238
52910-substrings
209
530GCD of Divisors
380
531Chinese leftovers
982
532Nanobots on Geodesics
268
533Minimum values of the Carmichael function
284
534Weak Queens
255
535Fractal Sequence
253
536Modulo power identity
245
537Counting tuples
536
538Maximum quadrilaterals
283
539Odd elimination
714
540Counting primitive Pythagorean triples
529
541Divisibility of Harmonic Number Denominators
173
542Geometric Progression with Maximum Sum
199
543Prime-Sum Numbers
593
544Chromatic Conundrum
208
545Faulhaber's Formulas
454
546The Floor's Revenge
199
547Distance of random points within hollow square laminae
182
548Gozinta Chains
527
549Divisibility of factorials
2416
550Divisor game
290