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Search: id:A008463
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| A008463 |
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Take sum of squares of digits of previous term. |
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+0
11
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| 9, 81, 65, 61, 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, 16, 37, 58, 89, 145, 42, 20, 4, 16, 37, 58, 89, 145
(list; graph; listen)
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OFFSET
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1,1
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REFERENCES
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R. Honsberger, Ingenuity in Math., Random House, 1970, p. 83.
A. Porges, A set of eight numbers, Amer. Math. Monthly, 52 (1945), 379-382.
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FORMULA
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Periodic with period 8.
a(n)=A000218(n+1). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 24 2008
a(n)=A080709(n-2) for n>4. [From M. F. Hasler (MHasler(AT)univ-ag.fr), May 24 2009]
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PROGRAM
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Contribution from M. F. Hasler (MHasler(AT)univ-ag.fr), May 24 2009: (Start)
(PARI) /* The given terms have been checked as follows: */
a=[/* paste the terms here */]; k=3; vector(#a, n, k=A003132(k))==a
/* PARI code: */ A008463(n)=[9, 81, 65, 61, 37, 58, 89, 145, 42, 20, 4, 16][if(n>12, (n-5)%8+5, n)]
/* This code has been checked as follows: */ k=3; vector(99, n, k=A003132(k))==vector(99, n, A008463(n)) \\\\ (End)
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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), A008460 (starting with 6), A008462 (starting with 8), A008463 (starting with 9), A139566 (starting with 15), A122065 (starting with 74169). [From M. F. Hasler (MHasler(AT)univ-ag.fr), May 24 2009]
Sequence in context: A117817 A107346 A014393 this_sequence A043087 A037414 A161147
Adjacent sequences: A008460 A008461 A008462 this_sequence A008464 A008465 A008466
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KEYWORD
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nonn,base
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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