A274006 Largest proper prime power divisor of n, or 1 if n is squarefree.

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

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: A300253 A212173 A366993 * A203025 A057521 A084885

Adjacent sequences: A274003 A274004 A274005 * A274007 A274008 A274009

Keyword

nonn

Author

Franklin T. Adams-Watters, Jun 06 2016

Status

approved