cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A255409 a(n) = the least k for which A255326(k) = n; positions of records in A255326.

Original entry on oeis.org

0, 1, 4, 18, 24, 27, 160, 1470, 1500, 1701, 1920, 2205, 25515, 27951, 392392, 424710, 429000, 481250, 500500, 8824530, 8825856, 185435250, 194922000, 204289085, 214451328
Offset: 0

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Author

Antti Karttunen, Mar 23 2015

Keywords

Comments

Upper bounds of a(25), ..., a(39) are 5144855625, 5167255808, 5418041805, 5449966080, 6041677950, 187630152192, 187692817422, 188598924800, 195087679875, 6235115927040, 6235116982094, 6827777110000, 7028593647075, 7229398816640, 7251520647683, respectively. - Hiroaki Yamanouchi, Mar 30 2015

Crossrefs

Cf. A255326.

Programs

  • Mathematica
    f[0] = 0; f[n_] := f[n] = 1 + f[n - Times @@ FactorInteger[n][[;; , 1]]]; seq[nmax_] := Module[{s = {}, f1, fm = -1}, Do[f1 = f[n]; If[f1 > fm, fm = f1; AppendTo[s, n]], {n, 0, nmax}]; s]; seq[510000] (* Amiram Eldar, Mar 04 2024 *)

Formula

Other identities:
For all n >= 0, A255326(a(n)) = n.

Extensions

a(14)-a(24) from Hiroaki Yamanouchi, Mar 30 2015
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