A374808 a(n) is the smallest number which can be represented as the sum of 3 distinct nonzero tetrahedral numbers in exactly n ways, or -1 if no such number exists.
15, 95, 305, 1795, 2366, 12740, 105080, 193060, 231560, 446995, 2422980, 4753420, 5490660, 8205340, 30594200, 137606920, 138532800, 350464520
Offset: 1
Examples
a(3) = 305 = 1 + 84 + 220 = 20 + 120 + 165 = 56 + 84 + 165.
Links
- Eric Weisstein's World of Mathematics, Tetrahedral Number
Extensions
a(12)-a(18) from Michael S. Branicky, Jul 21 2024