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A001273
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Smallest number that takes n steps to reach 1 under iteration of sum-of-squares-of-digits map (= smallest "happy number" of height n).
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5
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OFFSET
| 0,2
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COMMENTS
| Subsequent terms are too large to display in full.
a(8) = 3789*10^973-1 (3788 followed by 973 9's)
a(9) = 78889*10^((a(8)-305)/81)-1 (78888 followed by (421*10^973-34)/9 9's, specified by Warut Roonguthai for UPINT3)
a(10) = 259*10^((a(9)-93)/81)-1
a(11) = 179*10^((a(10)-114)/81)-1
a(12) = 47*10^((a(11)-52)/81)-1
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REFERENCES
| R. K. Guy, Unsolved Problems in Number Theory, Sect. E34. (2nd ed. UPINT2 = 1994, 3rd ed. UPINT3 = 2004)
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LINKS
| Tianxin Cai & Xia Zhou, On The Heights of Happy Numbers[broken link]
H. G. Grundman, E. A. Teeple, Heights of happy numbers and cubic happy numbers, Fib Quart. 41 (4) (2003) 301
H. Havermann, Big and Happy
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CROSSREFS
| Cf. A007770, A018785, A176762.
Sequence in context: A191969 A018785 A176762 * A111524 A074346 A126973
Adjacent sequences: A001270 A001271 A001272 * A001274 A001275 A001276
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KEYWORD
| base,nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| a(7), a(8) from Jud McCranie (JudMcCranie(AT)ugaalum.uga.edu), Sep 15 1994
a(9)-a(12) from Hans Havermann (gladhobo(AT)teksavvy.com), May 02 2010
Edited by Hans Havermann (gladhobo(AT)teksavvy.com), May 03 2010, May 04 2010
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