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Search: id:A067184
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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
1
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| 2, 3, 5, 7, 250, 735, 792, 2500, 4992, 9075, 11760, 25000, 30625, 67914, 91476
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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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
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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[ # ] &]
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CROSSREFS
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Cf. A006753.
Sequence in context: A029978 A122764 A064157 this_sequence A067170 A090719 A088297
Adjacent sequences: A067181 A067182 A067183 this_sequence A067185 A067186 A067187
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KEYWORD
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base,nonn
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AUTHOR
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Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Feb 18 2002
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