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Problems Archives

The problems archives table shows problems 1 to 617. 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
927
502Counting Castles
193
503Compromise or persist
238
504Square on the Inside
2073
505Bidirectional Recurrence
151
506Clock sequence
639
507Shortest Lattice Vector
144
508Integers in base i-1
160
509Divisor Nim
397
510Tangent Circles
751
511Sequences with nice divisibility properties
299
512Sums of totients of powers
1052
513Integral median
232
514Geoboard Shapes
153
515Dissonant Numbers
337
5165-smooth totients
1039
517A real recursion
350
518Prime triples and geometric sequences
1093
519Tricolored Coin Fountains
263
520Simbers
289
521Smallest prime factor
540
522Hilbert's Blackout
180
523First Sort I
657
524First Sort II
158
525Rolling Ellipse
354
526Largest prime factors of consecutive numbers
237
527Randomized Binary Search
519
528Constrained Sums
201
52910-substrings
149
530GCD of Divisors
277
531Chinese leftovers
734
532Nanobots on Geodesics
221
533Minimum values of the Carmichael function
237
534Weak Queens
221
535Fractal Sequence
218
536Modulo power identity
205
537Counting tuples
409
538Maximum quadrilaterals
244
539Odd elimination
583
540Counting primitive Pythagorean triples
418
541Divisibility of Harmonic Number Denominators
140
542Geometric Progression with Maximum Sum
167
543Prime-Sum Numbers
459
544Chromatic Conundrum
147
545Faulhaber's Formulas
365
546The Floor's Revenge
150
547Distance of random points within hollow square laminae
154
548Gozinta Chains
426
549Divisibility of factorials
1835
550Divisor game
211