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Problems Archives

The problems archives table shows problems 1 to 621. 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
1908
402Integer-valued polynomials
288
403Lattice points enclosed by parabola and line
274
404Crisscross Ellipses
252
405A rectangular tiling
460
406Guessing Game
292
407Idempotents
1768
408Admissible paths through a grid
430
409Nim Extreme
341
410Circle and tangent line
216
411Uphill paths
467
412Gnomon numbering
357
413One-child Numbers
291
414Kaprekar constant
211
415Titanic sets
228
416A frog's trip
215
417Reciprocal cycles II
640
418Factorisation triples
521
419Look and say sequence
381
4202x2 positive integer matrix
317
421Prime factors of n15+1
460
422Sequence of points on a hyperbola
201
423Consecutive die throws
345
424Kakuro
289
425Prime connection
1090
426Box-ball system
193
427n-sequences
213
428Necklace of circles
181
429Sum of squares of unitary divisors
1894
430Range flips
656
431Square Space Silo
465
432Totient sum
350
433Steps in Euclid's algorithm
369
434Rigid graphs
261
435Polynomials of Fibonacci numbers
770
436Unfair wager
330
437Fibonacci primitive roots
563
438Integer part of polynomial equation's solutions
221
439Sum of sum of divisors
251
440GCD and Tiling
262
441The inverse summation of coprime couples
271
442Eleven-free integers
294
443GCD sequence
809
444The Roundtable Lottery
218
445Retractions A
259
446Retractions B
247
447Retractions C
185
448Average least common multiple
237
449Chocolate covered candy
653
450Hypocycloid and Lattice points
157