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Problems Archives

The problems archives table shows problems 1 to 621. 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
190
503Compromise or persist
232
504Square on the Inside
2115
505Bidirectional Recurrence
151
506Clock sequence
641
507Shortest Lattice Vector
144
508Integers in base i-1
155
509Divisor Nim
397
510Tangent Circles
755
511Sequences with nice divisibility properties
297
512Sums of totients of powers
1054
513Integral median
228
514Geoboard Shapes
157
515Dissonant Numbers
333
5165-smooth totients
1059
517A real recursion
353
518Prime triples and geometric sequences
1109
519Tricolored Coin Fountains
260
520Simbers
286
521Smallest prime factor
538
522Hilbert's Blackout
181
523First Sort I
660
524First Sort II
159
525Rolling Ellipse
355
526Largest prime factors of consecutive numbers
234
527Randomized Binary Search
524
528Constrained Sums
198
52910-substrings
147
530GCD of Divisors
278
531Chinese leftovers
734
532Nanobots on Geodesics
219
533Minimum values of the Carmichael function
238
534Weak Queens
220
535Fractal Sequence
217
536Modulo power identity
202
537Counting tuples
408
538Maximum quadrilaterals
238
539Odd elimination
587
540Counting primitive Pythagorean triples
425
541Divisibility of Harmonic Number Denominators
140
542Geometric Progression with Maximum Sum
165
543Prime-Sum Numbers
467
544Chromatic Conundrum
148
545Faulhaber's Formulas
365
546The Floor's Revenge
151
547Distance of random points within hollow square laminae
148
548Gozinta Chains
424
549Divisibility of factorials
1878
550Divisor game
217