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A071440
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Start with 1; add the digits of the previous term and the squares of the digits of the previous term.
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2
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1, 2, 6, 42, 26, 48, 92, 96, 132, 20, 6, 42, 26, 48, 92, 96, 132, 20, 6, 42, 26, 48, 92, 96, 132, 20, 6, 42, 26, 48, 92, 96, 132, 20, 6, 42, 26, 48, 92, 96, 132, 20, 6, 42, 26, 48, 92, 96, 132, 20, 6, 42, 26, 48, 92, 96, 132, 20, 6, 42, 26, 48, 92, 96, 132, 20, 6, 42, 26, 48
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| The sequence becomes periodic after ten steps: a(10) = a(2). Period length is 8, length of the preperiodic part is 2. - Other starting values except 9, 90, 900, ... result in sequences which exhibit essentially the same behavior.
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EXAMPLE
| 42 -> 4 + 2 + 4^2 + 2^2 = 26, 26 -> 2 + 6 + 2^2 + 6^2 = 48, ...
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PROG
| (PARI) {m=70; a=1; for(j=1, m, print1(a, ", "); n=a; a=0; while(n>0, d=divrem(n, 10); n=d[1]; a=a+(1+d[2])*d[2]))}
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CROSSREFS
| Sequence in context: A000612 A096138 A004153 * A033936 A203618 A098814
Adjacent sequences: A071437 A071438 A071439 * A071441 A071442 A071443
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KEYWORD
| nonn,base,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Oct 23 2002
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EXTENSIONS
| Edited and extended by Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Oct 24 2002
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