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Search: id:A139566
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| A139566 |
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Take sum of squares of digits of previous term. |
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+0
11
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| 15, 26, 40, 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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FORMULA
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Periodic with period 8.
a(n)=(1/224)*{3295*(n mod 8)-1157*[(n+1) mod 8]-457*[(n+2) mod 8]-177*[(n+3) mod 8]-177*[(n+4) mod 8]+75*[(n+5) mod 8]+859*[(n+6) mod 8]+1027*[(n+7) mod 8]}-27*[C(2*n,n) mod 2]+6*[C((n+1)^2,n+3) mod 2]+36*[C(n^2,n+2) mod 2], with n>=0 - Paolo P. Lava (ppl(AT)spl.at), Jul 07 2008
a(n) = A008463(n) for n>4. [From M. F. Hasler (MHasler(AT)univ-ag.fr), May 24 2009]
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MATHEMATICA
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a = {15}; Do[AppendTo[a, Plus @@ (IntegerDigits[a[[ -1]]]^2)], {70}]; a - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Jun 14 2008
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PROGRAM
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Contribution from M. F. Hasler (MHasler(AT)univ-ag.fr), May 24 2009: (Start)
(PARI) /* to check the given terms */
a=[/* paste the terms here */ ]; k=(10^15-1)/9; a==vector(#%, n, k=A003132(k))
/* to check the following code, use: a==vector(99, n, A139566(n)) */
A139566(n)=[15, 26, 40, 16, 37, 58, 89, 145, 42, 20, 4][if(n>11, (n-4)%8+4, n)] \\\\ (End)
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CROSSREFS
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Cf. A101926 A087965 A074411 A110998 A051861 A048222.
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), A122065 (starting with 74169). [From M. F. Hasler (MHasler(AT)univ-ag.fr), May 24 2009]
Sequence in context: A050699 A097393 A050700 this_sequence A097963 A063936 A132452
Adjacent sequences: A139563 A139564 A139565 this_sequence A139567 A139568 A139569
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KEYWORD
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base,nonn
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AUTHOR
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Robert Gornall (rob(AT)khobbits.net), Jun 11 2008
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EXTENSIONS
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More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Jun 14 2008
Terms checked using the given PARI code. M. F. Hasler (MHasler(AT)univ-ag.fr), May 24 2009
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