A334013 a(n) is the least integer that is the sum of two nonzero tetrahedral numbers in exactly n ways.

2, 140, 102424, 43322844421220

Offset: 1

Author

Ilya Gutkovskiy, Apr 12 2020

Keywords

• nonn
• hard
• more

Examples

			Let Te(k) denote the k-th tetrahedral number, then
a(1) = Te(1) + Te(1);
a(2) = Te(7) + Te(6) = Te(8) + Te(4);
a(3) = Te(82) + Te(34) = Te(83) + Te(27) = Te(84) + Te(7);
a(4) = Te(60500) + Te(33760) = Te(53311) + Te(47682) = Te(63383) + Te(17423) = Te(63495) + Te(15790);
		

Links

• Eric Weisstein's World of Mathematics, Tetrahedral Number
• Index to sequences related to pyramidal numbers

Crossrefs

Cf. A000292, A010329, A011541, A053587.

Extensions

a(4) from Giovanni Resta, Apr 13 2020