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A056528
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Sum of digits of square of sum of digits of square.
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2
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1, 7, 9, 13, 13, 9, 16, 1, 9, 1, 7, 9, 13, 13, 9, 16, 10, 9, 1, 7, 9, 13, 13, 9, 16, 10, 9, 10, 16, 9, 13, 13, 9, 16, 1, 9, 10, 16, 9, 13, 13, 9, 16, 10, 9, 1, 16, 9, 13, 13, 9, 16, 10, 9, 1, 16, 9, 13, 13, 9, 16, 10, 18, 10, 16, 9, 13, 13, 9, 16, 1, 9, 10, 16, 9, 13, 13, 9, 16, 1, 9
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OFFSET
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1,2
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LINKS
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FORMULA
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EXAMPLE
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a(2)=7 because sum of digits of square of 2 is 4 and sum of digits of square of 4 is 1+6=7
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MATHEMATICA
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Array[Total[IntegerDigits[(Total[IntegerDigits[#^2]])^2]]&, 90] (* Harvey P. Dale, Jan 17 2012 *)
Table[Nest[Total[IntegerDigits[#^2]]&, n, 2], {n, 90}] (* Harvey P. Dale, Mar 07 2018 *)
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CROSSREFS
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Cf. A004159 for sum of digits of square, A056020 where iteration settles to 1, A056020 where iteration settles to 9, A056527 where iteration settles to 13 and 16. See also A056529.
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KEYWORD
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base,easy,nonn
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AUTHOR
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STATUS
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approved
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