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

1,1

Links

Table of n, a(n) for n=1..27.

Michael S. Branicky, Python program for A374141, A374142, and A374143

Eric Weisstein's World of Mathematics, Heptagonal Number

Example

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

Prog

(Python) # see linked program

Crossrefs

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

Sequence in context: A336941 A337842 A266317 * A080320 A083942 A274588

Adjacent sequences: A374139 A374140 A374141 * A374143 A374144 A374145

Keyword

nonn

Author

Ilya Gutkovskiy, Jun 28 2024

Extensions

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

Status

approved