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Problems Archives

The problems archives table shows problems 1 to 746. 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
1218
502Counting Castles
253
503Compromise or persist
285
504Square on the Inside
2853
505Bidirectional Recurrence
190
506Clock sequence
799
507Shortest Lattice Vector
193
508Integers in base i-1
212
509Divisor Nim
519
510Tangent Circles
938
511Sequences with nice divisibility properties
378
512Sums of totients of powers
1390
513Integral median
282
514Geoboard Shapes
194
515Dissonant Numbers
424
5165-smooth totients
1441
517A real recursion
422
518Prime triples and geometric sequences
1485
519Tricoloured Coin Fountains
314
520Simbers
369
521Smallest prime factor
682
522Hilbert's Blackout
242
523First Sort I
895
524First Sort II
197
525Rolling Ellipse
452
526Largest prime factors of consecutive numbers
279
527Randomized Binary Search
670
528Constrained Sums
253
52910-substrings
219
530GCD of Divisors
408
531Chinese leftovers
1036
532Nanobots on Geodesics
280
533Minimum values of the Carmichael function
297
534Weak Queens
265
535Fractal Sequence
263
536Modulo power identity
259
537Counting tuples
561
538Maximum quadrilaterals
298
539Odd elimination
748
540Counting primitive Pythagorean triples
572
541Divisibility of Harmonic Number Denominators
185
542Geometric Progression with Maximum Sum
208
543Prime-Sum Numbers
627
544Chromatic Conundrum
217
545Faulhaber's Formulas
473
546The Floor's Revenge
208
547Distance of random points within hollow square laminae
192
548Gozinta Chains
549
549Divisibility of factorials
2503
550Divisor game
309