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A090425
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Number of iterations required for happy number A007770(n) to converge to 1.
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0
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1, 6, 2, 3, 5, 4, 4, 3, 4, 5, 5, 3, 6, 4, 4, 3, 5, 5, 4, 2, 3, 5, 4, 3, 6, 6, 4, 4, 5, 5, 4, 6, 4, 4, 4, 6, 4, 6, 6, 6, 6, 4, 4, 6, 3, 4, 3, 6, 6, 4, 6, 6, 6, 5, 7, 6, 7, 6, 6, 6, 7, 5, 6, 6, 6, 7, 5, 5, 5, 4, 4, 7, 5, 5, 5, 7, 7, 4, 7, 4, 5, 3, 4, 6, 6, 6, 7, 6, 6, 4, 7, 7, 4, 5, 5, 4, 6, 3, 6, 7, 6, 4
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| The count includes both the start and end.
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LINKS
| Eric Weisstein's World of Mathematics, Happy Number
T. Cai, Xia Zhou, On the heights of happy numbers, Rocky Mount. J. Math. 38 (6) (2008) 1921. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 22 2010]
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EXAMPLE
| 7 is the 2nd happy number and iterated digit squarings and additions give the sequence {7,49,97,130,10,1}, so a(2)=6.
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CROSSREFS
| Cf. A007770.
Sequence in context: A134105 A167509 A011362 * A160081 A178054 A195453
Adjacent sequences: A090422 A090423 A090424 * A090426 A090427 A090428
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KEYWORD
| nonn,base
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AUTHOR
| Eric Weisstein (eric(AT)weisstein.com), Nov 30, 2003
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