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A087463 Generalized multiplicative Jacobsthal sequence. 3
0, 1, 1, 0, 5, 11, 0, 43, 85, 0, 341, 683, 0, 2731, 5461, 0, 21845, 43691, 0, 174763, 349525, 0, 1398101, 2796203, 0, 11184811, 22369621, 0, 89478485, 178956971, 0, 715827883, 1431655765, 0, 5726623061, 11453246123, 0, 45812984491 (list; graph; refs; listen; history; internal format)
OFFSET

0,5

COMMENTS

Set A001045(3n)=0 in A001045. 2^n=A087462(n)+A087463(n)+A087464(n) provides a decomposition of Pascal's triangle.

FORMULA

a(n)=sum{k=0..n, if (mod(nk, 3)=1, 1, 0)C(n, k)}; a(n)=(2/9)(1-cos(2pi*n/3))(2^n-(-1)^n).

CROSSREFS

Sequence in context: A048360 A067958 A201026 * A160366 A160923 A201457

Adjacent sequences:  A087460 A087461 A087462 * A087464 A087465 A087466

KEYWORD

easy,nonn

AUTHOR

Paul Barry (pbarry(AT)wit.ie), Sep 08 2003

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Last modified February 16 01:56 EST 2012. Contains 205860 sequences.