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## Problems Archives

The problems archives table shows problems 1 to 751. 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
401Sum of squares of divisors
2411
402Integer-valued polynomials
371
403Lattice points enclosed by parabola and line
335
404Crisscross Ellipses
307
405A rectangular tiling
571
406Guessing Game
353
407Idempotents
2327
534
409Nim Extreme
431
410Circle and tangent line
262
411Uphill paths
594
412Gnomon numbering
467
413One-child Numbers
357
414Kaprekar constant
257
415Titanic sets
284
416A frog's trip
278
417Reciprocal cycles II
799
418Factorisation triples
642
419Look and say sequence
453
4202x2 positive integer matrix
407
421Prime factors of n15+1
600
422Sequence of points on a hyperbola
253
423Consecutive die throws
452
424Kakuro
370
425Prime connection
1366
426Box-ball system
239
427n-sequences
281
428Necklace of circles
223
429Sum of squares of unitary divisors
2402
430Range flips
807
431Square Space Silo
573
432Totient sum
449
433Steps in Euclid's algorithm
443
434Rigid graphs
319
435Polynomials of Fibonacci numbers
1025
436Unfair wager
425
437Fibonacci primitive roots
734
438Integer part of polynomial equation's solutions
254
439Sum of sum of divisors
357
440GCD and Tiling
344
441The inverse summation of coprime couples
334
442Eleven-free integers
364
443GCD sequence
1059
444The Roundtable Lottery
283
445Retractions A
348
446Retractions B
328
447Retractions C
262
448Average least common multiple
313
449Chocolate covered candy
850
450Hypocycloid and Lattice points
179