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A359964 Refactorable numbers (A033950) having more divisors than all smaller refactorable numbers. 3
1, 2, 8, 12, 24, 36, 60, 180, 240, 360, 720, 1260, 1680, 3360, 5040, 10080, 15120, 20160, 25200, 30240, 55440, 100800, 110880, 221760, 277200, 443520, 665280, 720720, 1108800, 1441440, 2494800, 2882880, 3603600, 5765760, 8648640, 12972960, 14414400, 25945920, 28828800 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
The corresponding numbers of divisors are 1, 2, 4, 6, 8, 9, 12, 18, 20, 24, ... .
This sequence if infinite since there are refactorable numbers with arbitrarily large number of divisors. E.g., for any prime p, p^(p-1) is a refactorable number with p divisors.
LINKS
MATHEMATICA
seq[nmax_] := Module[{s = {}, dm = 0, d}, Do[d = DivisorSigma[0, n]; If[d > dm && Divisible[n, d], dm = d; AppendTo[s, n]], {n, 1, nmax}]; s]; seq[10^6]
PROG
(PARI) lista(nmax) = {my(dm = 0, d); for(n = 1, nmax, d = numdiv(n); if(d > dm && n%d == 0, dm = d; print1(n, ", "))); }
CROSSREFS
Subsequence of A033950.
Similar sequences: A002182, A335317, A356078, A359963.
Sequence in context: A162152 A280252 A013654 * A277804 A108978 A269968
KEYWORD
nonn
AUTHOR
Amiram Eldar, Jan 20 2023
STATUS
approved

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Last modified April 17 17:01 EDT 2024. Contains 371765 sequences. (Running on oeis4.)