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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: A073137 A131233 A136623 * A267508 A163382 A343127

Adjacent sequences:  A031215 A031216 A031217 * A031219 A031220 A031221

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Erich Friedman.

STATUS

approved

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Last modified April 12 22:36 EDT 2021. Contains 342933 sequences. (Running on oeis4.)