Number Recreations

What is New? (Update 6 October, 2014)

The page on Fascinating Factorials added.

CYF NO. 11 solution by David Harrison for a difficult and highly computational problem given.

CYF NO. 44 solution by Fred Schneider given.

CYF NO. 31 Comments by Paul Cleary given.

Do You Know?

Can You Find?

Contents

• Rare Numbers
• EPORNS(Equal Product Of Reversible Numbers)
• Unique Numbers
• Unlucky 13
• Fascinating Squares
• Curious Properties of 153
• Amicable Numbers (Including Happy and Harshad Amicable Pairs)
• Smarandache Sequence of Happy Numbers
• Fascinating Triangular Numbers
• Smith Numbers
• Cab Numbers
• Fascinating Factorials
• Happy numbers
• Kaprekar numbers
• Fibonacci Numbers
• Prime Polynomials
• Ramanujan Numbers
• Primes, Pseudoprimes & Strong Pseudoprimes

Note: The above topics including many more will be added in due course.

Prime Curios! - site maintained by G. L. Honaker Jr. and Chris Caldwell

• 1 2 3 5 6 7 11 13 14 19 23 25 27 28 29 31 41 45 51 53 65 75 89 101 124 140 142 149 153
• 177 199 207 220 233 299 567 645 663 726 821 1123 1297 1973 2441 3319 4023 4201
• 5387 5879 6318 6899 10201 15841 17163 65281 29929 88357 112583 129921 135799
• 161038 189375 206483 211673 632148 656601 755968 823799 853211 864203 975313
• 1346269 1618033 2024689 2718281 4463535 15966114 19999999 118689518 123456879
• 179376463 191735161 202536181 683441871 880346227 987634512 987653214 999828727
• 1023465798 1023479856 1234457689 1608906624 3778888999 9876534120 10234465789
• 100123456789 198765432101 399899999999999 29998999999999999999999
• 16180...05887 (280-digits)

  And many more

My Favorite Links

• The Prime Puzzles and Problems Connection by Carlos Rivera has lot of interesting material related to prime numbers.

• Lots of information on prime numbers can be found at the Prime Pages.

• Prime Curios!, by G. L. Honaker, Jr. & Chris Caldwell

• Eppstein's Number Theory by David Eppstein has number of simple Number Theoretic Algorithms.

• Magic Squares,Magic Stars and Other Interesting number patterns by Harvey Heinz

• Number Theory Web by Keith Matthews

• Mudd Math Fun Facts pages

• Eric Weissteins MathWorld Encyclopedia

• On-Line Encyclopedia of Integer Sequences OEIS

• Math Puzzles
  An interesting site with lot of math recreations by Ed Pegg Jr.

• Overview of Mathematician's Secret Room
  Challenges to the Unsolved Problems in Number Theory.

• Patrick De Geest's World!Of Numbers
  All about palindromic numbers and many other number recreations.

• World of Trotter Math
  Fascinating work on Number and other math recreations by dedicated mathematics teacher Terry Trotter.

• Steven Finch's Favorite Mathematical Constants
  All about Mathematical Constants.

• Smarandache Notions Journal
  All about Smarandache's work.