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ID
Description / Title
Solved By
251
Cardano Triplets
662
252
Convex Holes
512
253
Tidying up
521
254
Sums of Digit Factorials
536
255
Rounded Square Roots
507
256
Tatami-Free Rooms
431
257
Angular Bisectors
396
258
A lagged Fibonacci sequence
712
259
Reachable Numbers
721
260
Stone Game
678
261
Pivotal Square Sums
393
262
Mountain Range.
433
263
An engineers' dream come true
560
264
Triangle Centres
375
265
Binary Circles
2005
266
Pseudo Square Root
772
267
Billionaire
1439
268
Counting numbers with at least four distinct prime factors less than 100
701
269
Polynomials with at least one integer root
400
270
Cutting Squares
407
271
Modular Cubes, part 1
1009
272
Modular Cubes, part 2
449
273
Sum of Squares
669
274
Divisibility Multipliers
774
275
Balanced Sculptures
385
276
Primitive Triangles
545
277
A Modified Collatz sequence
1479
278
Linear Combinations of Semiprimes
511
279
Triangles with integral sides and an integral angle
395
280
Ant and seeds
517
281
Pizza Toppings
470
282
The Ackermann function
516
283
Integer sided triangles for which the area/perimeter ratio is integral.
397
284
Steady Squares
644
285
Pythagorean odds
612
286
Scoring probabilities
934
287
Quadtree encoding (a simple compression algorithm)
708
288
An enormous factorial
596
289
Eulerian Cycles
335
290
Digital Signature
526
291
Panaitopol Primes
628
292
Pythagorean Polygons
368
293
Pseudo-Fortunate Numbers
1126
294
Sum of digits - experience #23
467
295
Lenticular holes
329
296
Angular Bisector and Tangent
352
297
Zeckendorf Representation
1314
298
Selective Amnesia
393
299
Three similar triangles
392
300
Protein folding
507
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