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%I #29 Mar 28 2024 23:47:31
%S 1,2,3,4,5,5,7,8,9,9,11,11,13,13,13,16,17,17,19,19,19,19,23,23,25,25,
%T 27,27,29,29,31,32,32,32,32,32,37,37,37,37,41,41,43,43,43,43,47,47,49,
%U 49,49,49,53,53,53,53,53,53,59,59,61,61,61,64,64,64,67,67,67,67,71,71
%N Largest prime power <= n.
%C The length of the m-th run of {a(n)} is the length of the (m+1)-st run of A000015 for m > 1. - _Colin Linzer_, Mar 08 2024
%H Reinhard Zumkeller, <a href="/A031218/b031218.txt">Table of n, a(n) for n = 1..10000</a>
%H B. Dearden, J. Iiams, and J. Metzger, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL16/Dearden/dearden4.html">Rumor Arrays</a>, Journal of Integer Sequences, 16 (2013), #13.9.3.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/PrimePower.html">Prime Power</a>
%o (PARI) a(n)=if(n<1,0, while(matsize(factor(n))[1]>1,n--); n)
%o (Haskell)
%o a031218 n = last $ takeWhile (<= n) a000961_list
%o -- _Reinhard Zumkeller_, Apr 25 2011
%Y Cf. A000015, A000961.
%K nonn,easy
%O 1,2
%A _N. J. A. Sloane_
%E More terms from _Erich Friedman_
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