A381640 Numbers k such that f(k) > f(m) for all m < k, where f(k) = A381638(k)/A381639(k).
1, 6, 30, 105, 210, 2310, 15015, 30030, 255255, 510510, 1939938, 3233230, 4849845, 9699690, 111546435, 223092870, 3234846615, 6469693230
Offset: 1
Links
- Paul Erdős and Jean-Louis Nicolas, Grandes valeurs de fonctions liées aux diviseurs premiers consécutifs d'un entier, in: Jean-Marie de Koninck and Claude Levesque (eds.), Théorie des nombres / Number Theory, Proceedings of the International Number Theory Conference held at Université Laval, July 5-18, 1987, De Gruyter, 1989; alternative link.
Programs
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Mathematica
f[n_] := Module[{p = FactorInteger[n][[;; , 1]]}, Total[Most[p]/Rest[p]]]; seq[lim_] := Module[{fi, fmax = -1, s = {}}, Do[fi = f[i]; If[fi > fmax, fmax = fi; AppendTo[s, i]], {i, 1, lim}]; s]; seq[12000] -
PARI
f(n) = {my(p = factor(n)[,1]); sum(i = 1, #p-1, p[i]/p[i+1]);} list(lim) = {my(fm = -1, f1); for(k = 1, lim, f1 = f(k); if(f1 > fm, print1(k, ", "); fm = f1));}
Comments