Post #2658775
2026-05-06 08:50 UTC
@christianp@mathstodon.xyz Experimentally, asymptotically seems to be within
a(n) = n(n+3)/2 - o(n^0.5 log(n))
The peaks of (a(n) - n(n+3)/2)/n^0.5 seem to continue slowly growing, not sure if converging. Checked up to a(21710)=235694408 .
Replies (1)
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@hellman@mathstodon.xyz 2026-05-06 09:09
@christianp@mathstodon.xyz Wow! This extra ≈n^0.5 term actually precisely matches the index of n in a(n), when it is in the sequence (which happens very often, as mentioned) ! 😮 So for these cases we get a(n) = n(n+3)/2 - a.index(n) See the updated gist https://gist.github.com/hellman/a4a56f013085edf379ac6377db0fa9bb