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1, 6, 22, 90, 358, 1434, 5734, 22938, 91750, 367002, 1468006, 5872026, 23488102, 93952410, 375809638, 1503238554, 6012954214, 24051816858, 96207267430, 384829069722, 1539316278886, 6157265115546, 24629060462182, 98516241848730, 394064967394918, 1576259869579674
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,2
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LINKS
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N. J. A. Sloane, On the No. of ON Cells in Cellular Automata, Video of talk in Doron Zeilberger's Experimental Math Seminar at Rutgers University, Feb. 05 2015: Part 1, Part 2
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FORMULA
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G.f.: (1+3*x) / ((1+x)*(1-4*x)).
a(n) = (-2*(-1)^n + 7*4^n) / 5.
a(n) = 3*a(n-1) + 4*a(n-2) for n>1.
(End)
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MATHEMATICA
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PROG
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(PARI) Vec((1+3*x) / ((1+x)*(1-4*x)) + O(x^30)) \\ Colin Barker, Feb 04 2017
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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