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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
401Sum of squares of divisors
2018
402Integer-valued polynomials
297
403Lattice points enclosed by parabola and line
284
404Crisscross Ellipses
259
405A rectangular tiling
471
406Guessing Game
300
407Idempotents
1899
408Admissible paths through a grid
448
409Nim Extreme
351
410Circle and tangent line
221
411Uphill paths
499
412Gnomon numbering
365
413One-child Numbers
303
414Kaprekar constant
217
415Titanic sets
236
416A frog's trip
225
417Reciprocal cycles II
658
418Factorisation triples
540
419Look and say sequence
393
4202x2 positive integer matrix
334
421Prime factors of n15+1
489
422Sequence of points on a hyperbola
212
423Consecutive die throws
363
424Kakuro
306
425Prime connection
1138
426Box-ball system
196
427n-sequences
215
428Necklace of circles
187
429Sum of squares of unitary divisors
2019
430Range flips
687
431Square Space Silo
481
432Totient sum
366
433Steps in Euclid's algorithm
375
434Rigid graphs
265
435Polynomials of Fibonacci numbers
819
436Unfair wager
344
437Fibonacci primitive roots
593
438Integer part of polynomial equation's solutions
225
439Sum of sum of divisors
272
440GCD and Tiling
272
441The inverse summation of coprime couples
284
442Eleven-free integers
308
443GCD sequence
860
444The Roundtable Lottery
228
445Retractions A
271
446Retractions B
261
447Retractions C
187
448Average least common multiple
238
449Chocolate covered candy
708
450Hypocycloid and Lattice points
154