A374141 a(n) is the smallest number which can be represented as the sum of two distinct nonzero hexagonal numbers in exactly n ways, or -1 if no such number exists.

7, 384, 4995, 51106, 204805, 483031, 2443431, 4674256, 10476781, 17272531, 25600656, 60765331, 90406956, 206602126, 332808531, 481676406, 303826656, 435211156, 789949306, 1406495106, 2260173906, 2704798281, 3220562556, 4435869181, 5165053156, 5309576106, 9818788281

Offset: 1

Author

Ilya Gutkovskiy, Jun 28 2024

Keywords

• nonn

Examples

			a(2) = 384 = 6 + 378 = 153 + 231.
		

Links

• Michael S. Branicky, Table of n, a(n) for n = 1..39
• Michael S. Branicky, Python program for A374141, A374142, and A374143
• Eric Weisstein's World of Mathematics, Hexagonal Number

Crossrefs

Cf. A000384, A093195, A332989, A342326, A374142, A374143.

Programs

Python

# see linked program

Extensions

a(9)-a(27) from Michael S. Branicky, Jun 29 2024