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.

A072751 Greatest of the most frequent prime factors of squarefree numbers <= n; a(1)=1.

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%I A072751 #11 Nov 01 2024 12:05:52
%S A072751 1,2,3,5,3,3,2,2,2,2,2,2,2,3,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
%T A072751 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
%U A072751 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2
%N A072751 Greatest of the most frequent prime factors of squarefree numbers <= n; a(1)=1.
%C A072751 a(n)=2 for n>14.
%H A072751 Dominika Závacká, Cristina Dalfó, and Miquel Angel Fiol, <a href="https://ceur-ws.org/Vol-3792/paper19.pdf">Integer sequences from k-iterated line digraphs</a>, CEUR: Proc. 24th Conf. Info. Tech. - Appl. and Theory (ITAT 2024) Vol 3792, 156-161. See p. 161, Table 2.
%t A072751 max = 200; primeFactors = FactorInteger[#][[All, 1]]& /@ Select[Range[max], SquareFreeQ]; a[n_] := Sort[ Tally[ Take[ primeFactors, n] // Flatten], Which[#1[[2]] > #2[[2]], True, #1[[2]] == #2[[2]], #1[[1]] > #2[[1]], True, False]& ][[1, 1]]; Table[a[n], {n, 1, primeFactors // Length}] (* _Jean-François Alcover_, Oct 14 2013 *)
%Y A072751 Cf. A005117, A072747, A072748, A072749, A072750.
%K A072751 nonn,nice
%O A072751 1,2
%A A072751 _Reinhard Zumkeller_, Jul 08 2002