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Search: id:A080709
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| A080709 |
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Take sum of squares of digits of previous term. |
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+0
11
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| 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, 42, 20, 4, 16, 37
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Terms of the simple continued fraction of 75798937186/[sqrt(590163403297552587888099)-749562250137]. [From Paolo P. Lava (ppl(AT)spl.at), Aug 06 2009]
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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)=1/224*{859*(n mod 8)+1027*[(n+1) mod 8]+3295*[(n+2) mod 8]-1157*[(n+3) mod 8]-457*[(n+4) mod 8]-177*[(n+5) mod 8]-177*[(n+6) mod 8]+75*[(n+7) mod 8]} with n>=0 - Paolo P. Lava (ppl(AT)spl.at), Nov 27 2006
a(n) = A000216(n+1). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 19 2008]
a(n) = A003132(a(n-1)) for n>1; a(n) = A000218(n+11) = A000221(n+8) = A008460(n+14) = A008462(n+9) = A008463(n+10) = A122065(n+11) = A139566(n+10). [From M. F. Hasler (MHasler(AT)univ-ag.fr), May 24 2009]
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PROGRAM
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(PARI) A080709(n)=[4, 16, 37, 58, 89, 145, 42, 20][(n-1)%8+1] \\\\ [From M. F. Hasler (MHasler(AT)univ-ag.fr), May 24 2009]
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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), 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: A130279 A030158 A054246 this_sequence A080855 A103770 A121318
Adjacent sequences: A080706 A080707 A080708 this_sequence A080710 A080711 A080712
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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), Mar 04 2003
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