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Problems Archives

  • Problem 699 will be accessible in 3 hours, 49 minutes (Sunday, 26th January 2020, 10:00 am)

The problems archives table shows problems 1 to 688. 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
401Sum of squares of divisors
2163
402Integer-valued polynomials
327
403Lattice points enclosed by parabola and line
307
404Crisscross Ellipses
273
405A rectangular tiling
505
406Guessing Game
321
407Idempotents
2070
408Admissible paths through a grid
478
409Nim Extreme
394
410Circle and tangent line
242
411Uphill paths
542
412Gnomon numbering
415
413One-child Numbers
327
414Kaprekar constant
237
415Titanic sets
253
416A frog's trip
248
417Reciprocal cycles II
713
418Factorisation triples
580
419Look and say sequence
418
4202x2 positive integer matrix
363
421Prime factors of n15+1
531
422Sequence of points on a hyperbola
229
423Consecutive die throws
397
424Kakuro
327
425Prime connection
1235
426Box-ball system
210
427n-sequences
239
428Necklace of circles
203
429Sum of squares of unitary divisors
2201
430Range flips
736
431Square Space Silo
506
432Totient sum
403
433Steps in Euclid's algorithm
415
434Rigid graphs
289
435Polynomials of Fibonacci numbers
894
436Unfair wager
381
437Fibonacci primitive roots
651
438Integer part of polynomial equation's solutions
240
439Sum of sum of divisors
305
440GCD and Tiling
309
441The inverse summation of coprime couples
305
442Eleven-free integers
337
443GCD sequence
952
444The Roundtable Lottery
254
445Retractions A
308
446Retractions B
292
447Retractions C
219
448Average least common multiple
269
449Chocolate covered candy
770
450Hypocycloid and Lattice points
164