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A070274 Numbers n such that sum of digits of n equals the squarefree part of n. 7
1, 2, 3, 5, 6, 7, 12, 24, 100, 150, 200, 300, 320, 375, 500, 600, 640, 700, 704, 735, 832, 960, 1014, 1088, 1200, 1815, 2023, 2400, 2535, 2940, 3549, 3610, 3840, 4046, 4335, 4913, 5054, 5376, 5415, 5491, 6069, 6137, 6358, 6647, 7260, 7581, 7942, 8959, 9386 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The squarefree part of x, core(x), is the smallest integer such that x*core(x) is a square.

LINKS

Giovanni Resta, Table of n, a(n) for n = 1..10000

MATHEMATICA

core[n_]:=Block[{f=FactorInteger[n], p, e}, {p, e} = Transpose[f]; Times@@ (p^Mod[e, 2])]; Select[Range[10^4], core[#] == Plus @@ IntegerDigits[#] &] (* Giovanni Resta, Apr 21 2017 *)

PROG

(PARI) list(lim)=my(v=List()); forfactored(n=1, lim\1, if(core(n)==sumdigits(n[1]), listput(v, n[1]))); Vec(v) \\ Charles R Greathouse IV, Nov 05 2017

CROSSREFS

Cf. A007913, A057531, A057532, A050689, A070275, A063737, A067077, A285494.

Sequence in context: A270974 A039058 A046158 * A088968 A328451 A057924

Adjacent sequences:  A070271 A070272 A070273 * A070275 A070276 A070277

KEYWORD

nonn,base

AUTHOR

Benoit Cloitre, May 09 2002

EXTENSIONS

Data corrected by Giovanni Resta, Apr 21 2017

STATUS

approved

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Last modified October 23 03:21 EDT 2019. Contains 328335 sequences. (Running on oeis4.)