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Problems Archives

The problems archives table shows problems 1 to 652. 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
993
502Counting Castles
197
503Compromise or persist
242
504Square on the Inside
2366
505Bidirectional Recurrence
157
506Clock sequence
684
507Shortest Lattice Vector
148
508Integers in base i-1
162
509Divisor Nim
423
510Tangent Circles
808
511Sequences with nice divisibility properties
320
512Sums of totients of powers
1143
513Integral median
239
514Geoboard Shapes
162
515Dissonant Numbers
345
5165-smooth totients
1174
517A real recursion
369
518Prime triples and geometric sequences
1202
519Tricoloured Coin Fountains
271
520Simbers
304
521Smallest prime factor
575
522Hilbert's Blackout
182
523First Sort I
714
524First Sort II
158
525Rolling Ellipse
374
526Largest prime factors of consecutive numbers
234
527Randomized Binary Search
554
528Constrained Sums
207
52910-substrings
165
530GCD of Divisors
309
531Chinese leftovers
828
532Nanobots on Geodesics
227
533Minimum values of the Carmichael function
244
534Weak Queens
222
535Fractal Sequence
220
536Modulo power identity
212
537Counting tuples
447
538Maximum quadrilaterals
253
539Odd elimination
625
540Counting primitive Pythagorean triples
453
541Divisibility of Harmonic Number Denominators
141
542Geometric Progression with Maximum Sum
165
543Prime-Sum Numbers
508
544Chromatic Conundrum
164
545Faulhaber's Formulas
382
546The Floor's Revenge
163
547Distance of random points within hollow square laminae
154
548Gozinta Chains
447
549Divisibility of factorials
2057
550Divisor game
232