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A045541
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Square previous term and then delete digits of previous term.
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1
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2, 4, 16, 25, 6, 3, 9, 81, 656, 43033, 18518989, 3422322, 11718787168, 33299240224, 118856557176, 42330949, 17161, 29449992, 867300880006, 522114591215, 760366360676, 5815244491919, 3370600766306, 11949525822594424885
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| After 100 steps enters a cycle of length 307: a(n+307)=a(n) for n>100; a(167) = 88703778700083013187738001 is the largest term. [Reinhard Zumkeller, Sep 15 2011]
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LINKS
| Reinhard Zumkeller, Table of n, a(n) for n = 0..1000
Index to sequences with linear recurrences with constant coefficients
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EXAMPLE
| a(100)^2 = 46629^2 = 2174263641 --> 1731 = a(301);
a(407)^2 = 646^2 = 417316 --> 1731 = a(408) = a(301+307).
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MATHEMATICA
| nxt[n_]:=Module[{idn=IntegerDigits[n], idn2=IntegerDigits[n^2]}, Table[ idn2= DeleteCases[ idn2, idn[[i]]], {i, Length[idn]}]; FromDigits[idn2]]; NestList[nxt, 2, 30] (* From Harvey P. Dale, Oct 29 2011 *)
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PROG
| (Haskell)
a045541 n = a045541_list !! n
a045541_list = 2 : f 2 where
f x = x' : f x'
where x' = read $ filter (`notElem` show x) $ show (x^2)
-- Reinhard Zumkeller, Sep 15 2011
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CROSSREFS
| Sequence in context: A193868 A059622 A131475 * A153665 A015775 A104258
Adjacent sequences: A045538 A045539 A045540 * A045542 A045543 A045544
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KEYWORD
| base,nonn,nice
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AUTHOR
| Erich Friedman (erich.friedman(AT)stetson.edu)
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