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A023365 a(n) = 2^(3^(n-1)). 2
2, 8, 512, 134217728, 2417851639229258349412352, 14134776518227074636666380005943348126619871175004951664972849610340958208 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

a(n+1) = a(n) converted to base 8 from base 2 (written in base 10).

Number of disjunctive-normal forms of n-1 variables (either with x, or x-negated or without x). - Labos E. (labos(AT)ana.sote.hu), Jul 24 2003

a(n)*Psi(3^n,x), with the (monic) minimal polynomial Psi(3^n,x) of cos(2*Pi/3^n), becomes an integer polynomial with coefficient 1 of x^0.

  E.g., 8*Psi(9,x)=8*(x^3 - (3/4)*x + 1/8) = 8*x^3 - 6*x + 1.

  See A181875/A181876, A181877 and the W. Lang link under A181875. Wolfdieter Lang, Feb 24 2011.

FORMULA

a(n) = a(n-1)^3.

CROSSREFS

a(n) = A000079(A000244(n-1)).

Sequence in context: A000890 A033542 A098870 * A013554 A175923 A076985

Adjacent sequences:  A023362 A023363 A023364 * A023366 A023367 A023368

KEYWORD

nonn

AUTHOR

David W. Wilson (davidwwilson(AT)comcast.net)

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Last modified February 15 20:26 EST 2012. Contains 205852 sequences.