Friday, October 15, 2010

Recreation math & fun with Num3ers

Semiprime: a semiprime is a number of the form p*q where p and q are primes, not necessarily distinct.

http://en.wikipedia.org/wiki/Semiprime

http://mathworld.wolfram.com/Semiprime.html


For example,
842 (= 2 * 421) is a semiprime sandwiched between semiprimes: 841 and 843
841 = 29 * 29 = 29^2
843 = 3 * 281

Here's the list of the first 10,000 Primes :

http://primes.utm.edu/lists/small/10000.txt


For example, between consecutive primes 113 and 127 there are six semiprimes:
115 (=5*23), 118 (=2*59), 119 (=7*17), 121 (=11*11), 122 (=2*61), 123 (=3*41).

Could you find others?
And find a prime gap that is less and more than 6 semiprimes.

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