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A274006 Largest proper prime power divisor of n, or 1 if n is squarefree. 2
1, 1, 1, 4, 1, 1, 1, 8, 9, 1, 1, 4, 1, 1, 1, 16, 1, 9, 1, 4, 1, 1, 1, 8, 25, 1, 27, 4, 1, 1, 1, 32, 1, 1, 1, 9, 1, 1, 1, 8, 1, 1, 1, 4, 9, 1, 1, 16, 49, 25, 1, 4, 1, 27, 1, 8, 1, 1, 1, 4, 1, 1, 9, 64, 1, 1, 1, 4, 1, 1, 1, 9, 1, 1, 25, 4, 1, 1, 1, 16, 81, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

These values were mistakenly entered into A203025.

LINKS

Franklin T. Adams-Watters, Table of n, a(n) for n = 1..10000

EXAMPLE

36 = 2^2 * 3^2. 3^2 = 9 > 2^2 = 4, so a(36) = 9.

20 = 2^2 * 5, so 2^2 = 4 is the only proper prime power divisor of 20, thus a(20) = 4.

MATHEMATICA

Table[s = Select[FactorInteger[n], #[[2]] > 1 &]; If[s == {}, 1, Max[#1^#2 & @@@ s]], {n, 100}] (* T. D. Noe, Jan 02 2012 *)

PROG

(PARI) a(n) = my(fm=factor(n), r=1); for(k=1, #fm[, 1], if(fm[k, 2]!=1&&fm[k, 1]^fm[k, 2]>r, r=fm[k, 1]^fm[k, 2])); r

CROSSREFS

Cf. A203025, A246547.

Sequence in context: A088440 A300253 A212173 * A203025 A057521 A084885

Adjacent sequences:  A274003 A274004 A274005 * A274007 A274008 A274009

KEYWORD

nonn

AUTHOR

Franklin T. Adams-Watters, Jun 06 2016

STATUS

approved

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Last modified July 9 14:08 EDT 2020. Contains 335543 sequences. (Running on oeis4.)