A217196 Integers expressible in at least two ways as a^3 + b^4, where a,b > 0.

4097, 10729, 15641, 175625, 195193, 408536, 531442, 535537, 549017, 831209, 852984, 883664, 1778625, 3185784, 4258089, 5555233, 8876304, 11338448, 11402289, 12721424, 13844736, 16777217, 16781312, 17182440, 17308657, 19169848, 19703736, 22667633, 26248698

Offset: 1

Author

Frank Ruskey, Sep 27 2012

Keywords

• nonn

Comments

Numbers are listed in increasing order, no duplicates allowed (i.e., if the number is so expressible in 3 or more ways).

a(n) >> n^(12/7) by a counting argument. Can this be improved? Is there a corresponding upper bound? - Charles R Greathouse IV, Sep 27 2012

Examples

			a(1) = 4097 = 1^3 + 8^4 = 16^3 + 1^4 is the smallest such number.
		

Links

• Frank Ruskey, Table of n, a(n) for n = 1..5000