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===Names=== | ===Names=== | ||
This number is called the '''Hardy-Ramanujan number''' after a conversation between Hardy and Ramanujan where Ramanujan observed that it is the smallest number expressible as the sum of two cubes in two distinct ways: <math>\! 1729 = 10^3 + 9^ | This number is called the '''Hardy-Ramanujan number''' after a conversation between Hardy and Ramanujan where Ramanujan observed that it is the smallest number expressible as the sum of two cubes in two distinct ways: <math>\! 1729 = 10^3 + 9^3 = 12^3 + 1^3</math>. | ||
===Factorization=== | ===Factorization=== | ||
Revision as of 20:30, 2 January 2012
This article is about a particular natural number.|View all articles on particular natural numbers
Summary
Names
This number is called the Hardy-Ramanujan number after a conversation between Hardy and Ramanujan where Ramanujan observed that it is the smallest number expressible as the sum of two cubes in two distinct ways: .
Factorization
Properties and families
| Property or family | Parameter values | First few numbers |
|---|---|---|
| Carmichael number | third among them | 561, 1105, 1729, ... |
| Poulet number (Fermat pseudoprime to base 2) | sixth among them | 341, 561, 645, 1105, 1387, 1729, 1905, 2047 |