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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
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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FORMULA
| a(n)=A004159(A004159(n))
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EXAMPLE
| 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
| Array[Total[IntegerDigits[(Total[IntegerDigits[#^2]])^2]]&, 90] (* From Harvey P. Dale, Jan 17 2012 *)
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CROSSREFS
| 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.
Sequence in context: A174189 A112529 A161892 * A055565 A196088 A066498
Adjacent sequences: A056525 A056526 A056527 * A056529 A056530 A056531
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KEYWORD
| base,easy,nonn
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AUTHOR
| Henry Bottomley (se16(AT)btinternet.com), Jun 19 2000
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