A374143 a(n) is the smallest number which can be represented as the sum of two distinct nonzero octagonal numbers in exactly n ways, or -1 if no such number exists.
9, 1053, 12641, 68141, 365641, 953181, 2830641, 6232341, 13969041, 23211261, 104733741, 84994021, 175873641, 159851141, 538547641, 602713041, 810204416, 1019740041, 1053265741, 1972957241, 3339356041, 5914492241, 6886737541, 6388758241, 8902368041, 7858982841, 4942246941, 18439299341, 26639916441
Offset: 1
Keywords
Examples
a(2) = 1053 = 8 + 1045 = 408 + 645.
Links
- Michael S. Branicky, Table of n, a(n) for n = 1..38
- Michael S. Branicky, Python program for A374141, A374142, and A374143
- Eric Weisstein's World of Mathematics, Octagonal Number
Programs
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Python
# see linked program
Extensions
a(9)-a(29) from Michael S. Branicky, Jun 29 2024