A374142 a(n) is the smallest number which can be represented as the sum of two distinct nonzero heptagonal numbers in exactly n ways, or -1 if no such number exists.

8, 617, 8726, 255575, 1339801, 2419165, 9402323, 25764500, 35486953, 144568133, 385495261, 735503569, 638279039, 1183071664, 1571634527, 4449717748, 3584182298, 3871587494, 5693954599, 27084640649, 24205505111, 32489035067, 31973745058, 38935021406, 47570693867, 44749048300, 53075499329

Offset: 1

Author

Ilya Gutkovskiy, Jun 28 2024

Keywords

• nonn

Examples

			a(2) = 617 = 1 + 616 = 148 + 469.
		

Links

• Michael S. Branicky, Python program for A374141, A374142, and A374143
• Eric Weisstein's World of Mathematics, Heptagonal Number

Crossrefs

Cf. A000566, A093195, A332989, A342326, A374141, A374143.

Programs

Python

# see linked program

Extensions

a(8)-a(27) from Michael S. Branicky, Jun 29 2024