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Search: id:A122983
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| 1, 1, 3, 7, 21, 61, 183, 547, 1641, 4921, 14763, 44287, 132861, 398581, 1195743, 3587227, 10761681, 32285041, 96855123, 290565367, 871696101, 2615088301, 7845264903, 23535794707, 70607384121, 211822152361, 635466457083
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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Binomial transform is A063376.
A122983 = (1,1,3,7,1,1,3,7,...) mod 10. - M. F. Hasler, Feb 25 2008
Equals row sums of triangle A158301. [From Gary W. Adamson (qntmpkt(AT)yahoo.com), Mar 15 2009]
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LINKS
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M. F. Hasler, Table of n, a(n) for n=0,...,199.
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FORMULA
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G.f.: (1-2x-x^2)/((1-x)(1-2x-3x^2)); a(n)=3^n/4+(-1)^n/4+1/2;
E.g.f.: cosh(x)^2*exp(x); - Paul Barry (pbarry(AT)wit.ie), Jun 14 2007
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MAPLE
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BB := n->if n=0 then 1; elif n=1 then 1; else (3*BB(n-2)+2*BB(n-1)) fi: L:=[]: for k from 0 to 22 do L:=[op(L), ceil(BB(k)/2)]: od: L; - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Mar 19 2007, corrected by M. F. Hasler, Feb 25 2008
A122983 := n -> ceil(3^n/4); 'A122983(n)' $ n=0..22; # - M. F. Hasler, Feb 25 2008
a[ -1]:=1:a[0]:=1:a[1]:=3:for n from 2 to 50 do a[n]:=2*a[n-1]+3*a[n-2]-2 od: seq(a[n], n=-1..25); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 28 2008
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PROGRAM
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(PARI) A122983(n)=3^n\4+1 \\ - M. F. Hasler, Feb 25 2008
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CROSSREFS
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Cf. a(j+1) = A137822(2^j) and these are the record values of A137822.
A158301 [From Gary W. Adamson (qntmpkt(AT)yahoo.com), Mar 15 2009]
Sequence in context: A091486 A056779 A102877 this_sequence A005355 A025235 A129366
Adjacent sequences: A122980 A122981 A122982 this_sequence A122984 A122985 A122986
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KEYWORD
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easy,nonn
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Sep 22 2006
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EXTENSIONS
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Extended and corrected (existing Maple code) by M. F. Hasler (MHasler(AT)univ-ag.fr), Feb 25 2008
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