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A008460
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Take sum of squares of digits of previous term; start with 6.
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14
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6, 36, 45, 41, 17, 50, 25, 29, 85, 89, 145, 42, 20, 4, 16, 37, 58, 89, 145, 42, 20, 4, 16, 37, 58, 89, 145, 42, 20, 4, 16, 37, 58, 89, 145, 42, 20, 4, 16, 37, 58, 89, 145, 42, 20, 4, 16, 37, 58, 89, 145, 42, 20, 4, 16, 37, 58, 89, 145, 42, 20, 4, 16, 37, 58, 89, 145, 42, 20, 4
(list;
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refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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REFERENCES
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R. Honsberger, Ingenuity in Mathematics, Random House, 1970, p. 83.
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 1..100
Arthur Porges, A set of eight numbers, Amer. Math. Monthly 52 (1945), 379-382.
Index entries for linear recurrences with constant coefficients, signature (0, 0, 0, 0, 0, 0, 0, 1).
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FORMULA
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Periodic with period 8.
a(13+n) = A080709(n). - M. F. Hasler, May 24 2009
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MATHEMATICA
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NestList[Total[IntegerDigits[#]^2]&, 6, 80] (* Vincenzo Librandi, Jan 29 2013 *)
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PROG
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(PARI) A008460(n)=[6, 36, 45, 41, 17, 50, 25, 29, 85, 89, 145, 42, 20, 4, 16, 37, 58][if(n<18, n, (n-10)%8+10)] \\ M. F. Hasler, May 24 2009
(MAGMA) [6, 36, 45, 41, 17, 50, 25, 29, 85] cat &cat[[89, 145, 42, 20, 4, 16, 37, 58]: n in [0..17]]; // Vincenzo Librandi, Jan 29 2013
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CROSSREFS
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Cf. A003132 (the iterated map), A003621, A039943, A099645, A031176, A007770, A000216 (starting with 2), A000218 (starting with 3), A080709 (starting with 4), A000221 (starting with 5), A008462 (starting with 8), A008463 (starting with 9), A139566 (starting with 15), A122065 (starting with 74169). - M. F. Hasler, May 24 2009
Sequence in context: A043063 A328466 A232137 * A132633 A047792 A178909
Adjacent sequences: A008457 A008458 A008459 * A008461 A008462 A008463
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KEYWORD
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nonn,base
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AUTHOR
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N. J. A. Sloane
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EXTENSIONS
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An erroneous (duplicate) term deleted by M. F. Hasler, May 24 2009
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STATUS
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approved
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