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Problems Archives

The problems archives table shows problems 1 to 739. 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
1205
502Counting Castles
249
503Compromise or persist
283
504Square on the Inside
2828
505Bidirectional Recurrence
190
506Clock sequence
792
507Shortest Lattice Vector
189
508Integers in base i-1
209
509Divisor Nim
517
510Tangent Circles
928
511Sequences with nice divisibility properties
378
512Sums of totients of powers
1372
513Integral median
279
514Geoboard Shapes
193
515Dissonant Numbers
421
5165-smooth totients
1425
517A real recursion
419
518Prime triples and geometric sequences
1467
519Tricoloured Coin Fountains
313
520Simbers
364
521Smallest prime factor
679
522Hilbert's Blackout
238
523First Sort I
887
524First Sort II
189
525Rolling Ellipse
450
526Largest prime factors of consecutive numbers
274
527Randomized Binary Search
660
528Constrained Sums
246
52910-substrings
215
530GCD of Divisors
399
531Chinese leftovers
1015
532Nanobots on Geodesics
279
533Minimum values of the Carmichael function
294
534Weak Queens
264
535Fractal Sequence
258
536Modulo power identity
251
537Counting tuples
556
538Maximum quadrilaterals
294
539Odd elimination
732
540Counting primitive Pythagorean triples
555
541Divisibility of Harmonic Number Denominators
180
542Geometric Progression with Maximum Sum
202
543Prime-Sum Numbers
613
544Chromatic Conundrum
212
545Faulhaber's Formulas
468
546The Floor's Revenge
203
547Distance of random points within hollow square laminae
189
548Gozinta Chains
543
549Divisibility of factorials
2475
550Divisor game
304