

A031218


Largest prime power <= n.


9



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, 27, 27, 29, 29, 31, 32, 32, 32, 32, 32, 37, 37, 37, 37, 41, 41, 43, 43, 43, 43, 47, 47, 49, 49, 49, 49, 53, 53, 53, 53, 53, 53, 59, 59, 61, 61, 61, 64, 64, 64, 67, 67, 67, 67, 71, 71
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,2


LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
B. Dearden, J. Iiams, J. Metzger, Rumor Arrays, Journal of Integer Sequences, 16 (2013), #13.9.3.
Eric Weisstein's World of Mathematics, Prime Power


PROG

(PARI) a(n)=if(n<1, 0, while(matsize(factor(n))[1]>1, n); n)
(Haskell)
a031218 n = last $ takeWhile (<= n) a000961_list
 Reinhard Zumkeller, Apr 25 2011


CROSSREFS

Cf. A000015, A000961.
Sequence in context: A345965 A131233 A136623 * A357004 A357005 A267508
Adjacent sequences: A031215 A031216 A031217 * A031219 A031220 A031221


KEYWORD

nonn,easy


AUTHOR

N. J. A. Sloane.


EXTENSIONS

More terms from Erich Friedman.


STATUS

approved



