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A034684 If n = p_1^e_1 * ... * p_k^e_k, p_1 < ... < p_k primes, then a(n) = min { p_i^e_i }. 19
1, 2, 3, 4, 5, 2, 7, 8, 9, 2, 11, 3, 13, 2, 3, 16, 17, 2, 19, 4, 3, 2, 23, 3, 25, 2, 27, 4, 29, 2, 31, 32, 3, 2, 5, 4, 37, 2, 3, 5, 41, 2, 43, 4, 5, 2, 47, 3, 49, 2, 3, 4, 53, 2, 5, 7, 3, 2, 59, 3, 61, 2, 7, 64, 5, 2, 67, 4, 3, 2, 71, 8, 73, 2, 3, 4, 7, 2, 79, 5, 81, 2, 83, 3, 5, 2, 3, 8, 89, 2, 7, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(1) = 1; for n > 1, smallest unitary divisor of n that is larger than 1.

LINKS

T. D. Noe, Table of n, a(n) for n=1..1000

FORMULA

a(n) = min{A141809(n,k): k=1..A001221(n)}. - Reinhard Zumkeller, Jan 29 2013

MATHEMATICA

A034684[n_]:=Min[(#[[1]]^#[[2]])&/@FactorInteger[n]]; Array[A034684, 100] (* Enrique PĂ©rez Herrero, Nov 01 2011 *)

PROG

(PARI) A034684(n) = {local(f, m); if(n==1, 1, f=factor(n); m=f[1, 1]^f[1, 2]; for(i=1, matsize(f)[1], m=min(m, f[i, 1]^f[i, 2])); m)} [From Michael B. Porter, Jan 28 2010]

(Haskell)

a034684 = minimum . a141809_row  -- Reinhard Zumkeller, Jan 29 2013

CROSSREFS

Cf. A020639, A006530, A034684, A028233, A034699, A053585.

Cf. A034444, A034448, A052125.

Cf. A008475.

Sequence in context: A244734 A230089 A081811 * A028233 A216972 A066296

Adjacent sequences:  A034681 A034682 A034683 * A034685 A034686 A034687

KEYWORD

nonn,nice,easy

AUTHOR

Erich Friedman

STATUS

approved

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Last modified December 16 07:41 EST 2017. Contains 296076 sequences.