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A033478
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3x+1 sequence beginning at 3.
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23
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3, 10, 5, 16, 8, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,1
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REFERENCES
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C. A. Pickover, The Math Book, Sterling, NY, 2009; see p. 374.
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LINKS
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FORMULA
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G.f.: (3 + 10*x + 5*x^2 + 13*x^3 - 2*x^4 - x^5 - 14*x^6 - 7*x^7) / ((1 - x)*(1 + x + x^2)).
a(n) = a(n-3) for n>7.
(End)
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MAPLE
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f:=proc(n) if n mod 2 = 0 then n/2 else 3*n+1; fi; end; g:=proc(n) local i, t1; t1:=[n]; for i from 1 to 120 do t1:=[op(t1), f(t1[nops(t1)])]; od; t1; end; g(3);
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MATHEMATICA
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A033478list[nmax_]:=PadRight[{3, 10, 5, 16, 8}, nmax+1, {2, 1, 4}]; A033478list[100] (* Paolo Xausa, May 31 2023 *)
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PROG
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(PARI) Vec((3 + 10*x + 5*x^2 + 13*x^3 - 2*x^4 - x^5 - 14*x^6 - 7*x^7) / ((1 - x)*(1 + x + x^2)) + O(x^80)) \\ Colin Barker, Oct 04 2019
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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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