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Search: id:A039943
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| A039943 |
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Every integer eventually goes to one of these under the x goes to sum of squares of digits map. |
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+0
11
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OFFSET
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0,3
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COMMENT
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The subset of the first three terms would also satisfy the current definition. An alternate definition would be: Periodic points of A003132. [From M. F. Hasler (MHasler(AT)univ-ag.fr), May 24 2009]
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REFERENCES
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A. Porges, A set of eight numbers, Amer. Math. Monthly, 52 (1945), 379-382.
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LINKS
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Eric Weisstein's World of Mathematics, Happy Number
Wikipedia, Periodic point. [From M. F. Hasler (MHasler(AT)univ-ag.fr), May 24 2009]
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MATHEMATICA
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lst = {}; Do[a = NestWhile[Plus @@ (IntegerDigits@#^2) &, n, Unequal, All]; If[FreeQ[lst, a], AppendTo[lst, a]], {n, 10^4}] (from Robert G. Wilson v (rgwv(at)rgwv.com), Jan 19 2006)
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CROSSREFS
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Cf. A000216, A003621.
Cf. A003132 (the iterated map), A003621, A039943, A031176, A007770, A000216 (orbit of 2), A000218 (orbit of 3), A080709 (orbit of 4, the only nontrivial limit cycle), A000221 (orbit of 5), A008460 (orbit of 6), A008462 (orbit of 8), A008463 (orbit of 9), A139566 (orbit of 15), A122065 (orbit of 74169). [From M. F. Hasler (MHasler(AT)univ-ag.fr), May 24 2009]
Sequence in context: A146510 A032827 A071966 this_sequence A067671 A075331 A065661
Adjacent sequences: A039940 A039941 A039942 this_sequence A039944 A039945 A039946
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KEYWORD
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nonn,fini,full,base
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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