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.
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.
Terms
- a(0) =9a(1) =1053a(2) =12641a(3) =68141a(4) =365641a(5) =953181a(6) =2830641a(7) =6232341a(8) =13969041a(9) =23211261a(10) =104733741a(11) =84994021a(12) =175873641a(13) =159851141a(14) =538547641a(15) =602713041a(16) =810204416a(17) =1019740041a(18) =1053265741a(19) =1972957241a(20) =3339356041a(21) =5914492241a(22) =6886737541a(23) =6388758241a(24) =8902368041a(25) =7858982841a(26) =4942246941a(27) =18439299341a(28) =26639916441
External references
- oeis: A374143