Mathematical Fun Stuff

Integer Sequences
Do you recognize the sequence 1, 2, 5, 14, 42, 132, 429, ... ? Do you know what the next term should be? Check out the index of integer sequences maintained by Neil Sloane. (Yes, I know, the number of sequences that start out this way is infinite, but the sequence of Catalan numbers is the only one that I know of that is interesting or useful.)

Inverse Symbolic Calculator
Do you recognize the real number 1.6180339887 ... ? Look it up in the Inverse Symbolic Calculator, a project of the Centre for Experimental & Constructive Mathematics, and you will find that it matches the number (1 + sqrt(5))/2, the "golden ratio".

Erdös Number Project
Do you know your Erdös number? Do you know what an Erdös number is? Find out at the Erdös Number Project Home Page, maintained by Jerry Grossman and Patrick Ion. (My Erdös number is 2.)

Theoretical Computer Science Genealogy
Who was Donald Knuth's Ph.D. advisor? Did Alan Turing have any Ph.D. students? Find out by consulting the Theoretical Computer Science Genealogy project of SIGACT. My academic ancestors include Frank Harary, Alfred Foster, Alonzo Church, Oswald Veblen, E. H. Moore, and H. A. Newton. My great uncles include Stephen Kleene, Alan Turing, John Kemeny, Hartley Rogers, Michael Rabin, Dana Scott, Raymond Smullyan, and others, all students of Church. Check out your own academic family tree.

The Mathematics Genealogy Project
Mathematicians are playing the genealogy game now, too. This project is attempting to build a data base of all people who have received a doctorate in mathematics. When I last checked, there were 8 mathematicians named Newton in the database, but none with first name Issac.

Frequently Asked Questions in Mathematics
Has Fermat's Last Theorem been proved? What is the largest known prime number? How can one compute the digits of pi? Is 0.999 ... really equal to 1? Who is Nicholas Bourbaki? What is the Monty Hall Problem? Find answers to these and scores of other questions about mathematics at the Web Site of the sci.math FAQ team, lead by Alex López-Ortiz. He also maintains a Frequently Asked Questions in Theoretical Computer Science page, but it's a little rough yet.

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Last updated 25 July 2005