The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A309048 Expansion of Product_{k>=0} (1 + x^(3^k) + x^(2*3^k) - x^(3^(k+1))). 4
 1, 1, 1, 0, 1, 1, 0, 1, 1, -1, 0, 0, 1, 1, 1, 0, 1, 1, -1, 0, 0, 1, 1, 1, 0, 1, 1, -2, -1, -1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 0, 1, 1, 0, 1, 1, -1, 0, 0, 1, 1, 1, 0, 1, 1, -2, -1, -1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 0, 1, 1, 0, 1, 1, -1, 0, 0, 1, 1, 1, 0, 1, 1, -3, -2, -2, 1, -1, -1, 0, -1, -1, 2, 1, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,28 LINKS FORMULA G.f. A(x) satisfies: A(x) = (1 + x + x^2 - x^3) * A(x^3). a(0) = 1; a(3*n) = a(n) - a(n-1), a(3*n+1) = a(n), a(3*n+2) = a(n). MATHEMATICA nmax = 109; CoefficientList[Series[Product[(1 + x^(3^k) + x^(2 3^k) - x^(3^(k + 1))), {k, 0, Floor[Log[3, nmax]] + 1}], {x, 0, nmax}], x] nmax = 109; A[_] = 1; Do[A[x_] = (1 + x + x^2 - x^3) A[x^3] + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x] a[0] = 1; a[n_] := Switch[Mod[n, 3], 0, a[n/3] - a[(n - 3)/3], 1, a[(n - 1)/3], 2, a[(n - 2)/3]]; Table[a[n], {n, 0, 109}] CROSSREFS Cf. A005590, A054390, A309047. Sequence in context: A316867 A127327 A321144 * A086072 A086009 A086010 Adjacent sequences:  A309045 A309046 A309047 * A309049 A309050 A309051 KEYWORD sign AUTHOR Ilya Gutkovskiy, Jul 09 2019 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 26 14:45 EDT 2021. Contains 347668 sequences. (Running on oeis4.)