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ID
Description / Title
Solved By
251
Cardano Triplets
723
252
Convex Holes
545
253
Tidying up
580
254
Sums of Digit Factorials
575
255
Rounded Square Roots
548
256
Tatami-Free Rooms
458
257
Angular Bisectors
424
258
A lagged Fibonacci sequence
787
259
Reachable Numbers
796
260
Stone Game
745
261
Pivotal Square Sums
422
262
Mountain Range.
467
263
An engineers' dream come true
610
264
Triangle Centres
394
265
Binary Circles
2214
266
Pseudo Square Root
882
267
Billionaire
1604
268
Counting numbers with at least four distinct prime factors less than 100
776
269
Polynomials with at least one integer root
434
270
Cutting Squares
436
271
Modular Cubes, part 1
1140
272
Modular Cubes, part 2
505
273
Sum of Squares
739
274
Divisibility Multipliers
842
275
Balanced Sculptures
410
276
Primitive Triangles
618
277
A Modified Collatz sequence
1601
278
Linear Combinations of Semiprimes
547
279
Triangles with integral sides and an integral angle
420
280
Ant and seeds
569
281
Pizza Toppings
509
282
The Ackermann function
562
283
Integer sided triangles for which the area/perimeter ratio is integral.
424
284
Steady Squares
715
285
Pythagorean odds
656
286
Scoring probabilities
1028
287
Quadtree encoding (a simple compression algorithm)
769
288
An enormous factorial
660
289
Eulerian Cycles
348
290
Digital Signature
560
291
Panaitopol Primes
679
292
Pythagorean Polygons
388
293
Pseudo-Fortunate Numbers
1256
294
Sum of digits - experience #23
500
295
Lenticular holes
344
296
Angular Bisector and Tangent
372
297
Zeckendorf Representation
1447
298
Selective Amnesia
424
299
Three similar triangles
418
300
Protein folding
570
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