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Problems Archives

The problems archives table shows problems 1 to 632. 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.


IDDescription / TitleSolved By
501Eight Divisors
952
502Counting Castles
191
503Compromise or persist
234
504Square on the Inside
2242
505Bidirectional Recurrence
151
506Clock sequence
664
507Shortest Lattice Vector
143
508Integers in base i-1
159
509Divisor Nim
405
510Tangent Circles
780
511Sequences with nice divisibility properties
303
512Sums of totients of powers
1100
513Integral median
230
514Geoboard Shapes
150
515Dissonant Numbers
335
5165-smooth totients
1110
517A real recursion
357
518Prime triples and geometric sequences
1162
519Tricoloured Coin Fountains
260
520Simbers
294
521Smallest prime factor
547
522Hilbert's Blackout
174
523First Sort I
679
524First Sort II
156
525Rolling Ellipse
361
526Largest prime factors of consecutive numbers
229
527Randomized Binary Search
538
528Constrained Sums
199
52910-substrings
149
530GCD of Divisors
295
531Chinese leftovers
789
532Nanobots on Geodesics
218
533Minimum values of the Carmichael function
238
534Weak Queens
215
535Fractal Sequence
213
536Modulo power identity
202
537Counting tuples
416
538Maximum quadrilaterals
241
539Odd elimination
606
540Counting primitive Pythagorean triples
432
541Divisibility of Harmonic Number Denominators
137
542Geometric Progression with Maximum Sum
162
543Prime-Sum Numbers
482
544Chromatic Conundrum
155
545Faulhaber's Formulas
369
546The Floor's Revenge
154
547Distance of random points within hollow square laminae
152
548Gozinta Chains
428
549Divisibility of factorials
1965
550Divisor game
219