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Problems Archives

The problems archives table shows problems 1 to 641. 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
1982
402Integer-valued polynomials
292
403Lattice points enclosed by parabola and line
278
404Crisscross Ellipses
254
405A rectangular tiling
465
406Guessing Game
297
407Idempotents
1851
408Admissible paths through a grid
438
409Nim Extreme
342
410Circle and tangent line
218
411Uphill paths
490
412Gnomon numbering
361
413One-child Numbers
298
414Kaprekar constant
214
415Titanic sets
236
416A frog's trip
224
417Reciprocal cycles II
649
418Factorisation triples
535
419Look and say sequence
389
4202x2 positive integer matrix
331
421Prime factors of n15+1
477
422Sequence of points on a hyperbola
210
423Consecutive die throws
358
424Kakuro
306
425Prime connection
1127
426Box-ball system
196
427n-sequences
217
428Necklace of circles
188
429Sum of squares of unitary divisors
1983
430Range flips
678
431Square Space Silo
476
432Totient sum
360
433Steps in Euclid's algorithm
370
434Rigid graphs
263
435Polynomials of Fibonacci numbers
804
436Unfair wager
338
437Fibonacci primitive roots
582
438Integer part of polynomial equation's solutions
223
439Sum of sum of divisors
268
440GCD and Tiling
268
441The inverse summation of coprime couples
276
442Eleven-free integers
301
443GCD sequence
846
444The Roundtable Lottery
220
445Retractions A
266
446Retractions B
254
447Retractions C
188
448Average least common multiple
236
449Chocolate covered candy
699
450Hypocycloid and Lattice points
152