Almost prime
A two-digit number ab is called almost prime if one obtains a two-digit prime number by changing at most one of its digits a and b. (For example, 18 is an almost prime number because 13 is a prime number).
is called almost prime if one obtains a two-digit prime number by changing at most one of its digits and
(For example, 18 is an almost prime number because 13 is a prime number).[1][2][3]
Almost Prime Media
Demonstration, with Cuisenaire rods, of the 2-almost prime nature of the number 6
References
- ↑ Sándor, József. Handbook of Number Theory I (2006)Springer. p. 316. ISBN 978-1-4020-4215-7. doi:10.1007/1-4020-3658-2.
- ↑ Rényi, Alfréd A.. On the representation of an even number as the sum of a single prime and single almost-prime number (in ru). Izvestiya Rossiiskoi Akademii Nauk. Seriya Matematicheskaya 12 (1) (1948). p. 57–78.
- ↑ Heath-Brown, D. R.. Almost-primes in arithmetic progressions and short intervals. Mathematical Proceedings of the Cambridge Philosophical Society 83 (3) (May 1978). p. 357–375. doi:10.1017/S0305004100054657.