A374194 a(n) is the smallest number which can be represented as the sum of two nonzero hexagonal pyramidal numbers in exactly n ways, or -1 if no such number exists.

2, 5972, 5170425

Offset

1,1

Comments

There are no further positive terms <= 10^15. - Michael S. Branicky, Jun 30 2024

Links

Table of n, a(n) for n=1..3.

Eric Weisstein's World of Mathematics, Hexagonal Pyramidal Number

Example

a(2) = 5972 = 1222 + 4750 = 1925 + 4047.

Crossrefs

Cf. A002412, A011541, A334013, A374141, A374168, A374193.

Sequence in context: A057645 A129060 A190127 * A099690 A196750 A349512

Adjacent sequences: A374191 A374192 A374193 * A374195 A374196 A374197

Keyword

nonn,hard,more,bref

Author

Ilya Gutkovskiy, Jun 30 2024

Status

approved