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A067184
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Numbers n such that sum of the squares of the prime factors of n equals the sum of the squares of the digits of n.
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0
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2, 3, 5, 7, 250, 735, 792, 2500, 4992, 9075, 11760, 25000, 30625, 67914, 91476, 117600, 185625, 187278, 250000, 264992, 523908, 630784, 855360, 1082565, 1176000, 2395008, 2500000, 2546775, 2898350, 3608550, 3833280, 4299750
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| The prime factors of 4992 are 2,3,13, the sum of whose squares = 182 = sum of the squares of 4,9,9,2; so 4992 is a term of the sequence.
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MATHEMATICA
| f[n_] := Module[{a, l, t, r}, a = FactorInteger[n]; l = Length[a]; t = Table[a[[i]][[1]], {i, 1, l}]; r = Sum[(t[[i]])^2, {i, 1, l}]]; g[n_] := Module[{b, m, s}, b = IntegerDigits[n]; m = Length[b]; s = Sum[(b[[i]])^2, {i, 1, m}]]; Select[Range[2, 10^5], f[ # ] == g[ # ] &]
Select[Range[2, 4300000], Total[Transpose[FactorInteger[#]][[1]]^2]== Total[ IntegerDigits[#]^2]&] (* From Harvey P. Dale, Sep 01 2011 *)
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CROSSREFS
| Cf. A006753.
Sequence in context: A195302 A064157 A178371 * A067170 A090719 A088297
Adjacent sequences: A067181 A067182 A067183 * A067185 A067186 A067187
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KEYWORD
| base,nonn
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AUTHOR
| Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Feb 18 2002
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EXTENSIONS
| a(16)-a(32) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Sep 29 2009
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