

A151904


a(n) = (3^(wt(k)+f(j))1)/2 if n = 6k+j, 0 <= j < 6, where wt = A000120, f = A151899.


6



0, 0, 1, 1, 1, 4, 1, 1, 4, 4, 4, 13, 1, 1, 4, 4, 4, 13, 4, 4, 13, 13, 13, 40, 1, 1, 4, 4, 4, 13, 4, 4, 13, 13, 13, 40, 4, 4, 13, 13, 13, 40, 13, 13, 40, 40, 40, 121, 1, 1, 4, 4, 4, 13, 4, 4, 13, 13, 13, 40, 4, 4, 13, 13, 13, 40, 13, 13, 40, 40, 40, 121, 4, 4, 13, 13, 13, 40, 13, 13, 40, 40, 40
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OFFSET

0,6


LINKS

Table of n, a(n) for n=0..82.
David Applegate, Omar E. Pol and N. J. A. Sloane, The Toothpick Sequence and Other Sequences from Cellular Automata, Congressus Numerantium, Vol. 206 (2010), 157191. [There is a typo in Theorem 6: (13) should read u(n) = 4.3^(wt(n1)1) for n >= 2.]
N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS


FORMULA

a(n) = (3^A151902(n)1)/2.


MAPLE

f := proc(n) local j; j:=n mod 6; if (j<=1) then 0 elif (j<=4) then 1 else 2; fi; end;
wt := proc(n) local w, m, i; w := 0; m := n; while m > 0 do i := m mod 2; w := w+i; m := (mi)/2; od; w; end;
A151904 := proc(n) local k, j; k:=floor(n/6); j:=n6*k; (3^(wt(k)+f(j))1)/2; end;


PROG

(PARI) a(n)=(3^(hammingweight(n\6)+[0, 0, 1, 1, 1, 2][n%6+1])1)/2 \\ Charles R Greathouse IV, Sep 26 2015


CROSSREFS

Cf, A151899, A151902, A151905A151907.
Sequence in context: A183374 A176263 A110812 * A222360 A222371 A222479
Adjacent sequences: A151901 A151902 A151903 * A151905 A151906 A151907


KEYWORD

nonn,easy


AUTHOR

N. J. A. Sloane, Jul 31 2009


STATUS

approved



