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 A257196 Expansion of (1 + x) * (1 + x^5) / ((1 + x^2) * (1 + x^4)) in powers of x. 2
 1, 1, -1, -1, 0, 1, 1, -1, 0, 1, -1, -1, 0, 1, 1, -1, 0, 1, -1, -1, 0, 1, 1, -1, 0, 1, -1, -1, 0, 1, 1, -1, 0, 1, -1, -1, 0, 1, 1, -1, 0, 1, -1, -1, 0, 1, 1, -1, 0, 1, -1, -1, 0, 1, 1, -1, 0, 1, -1, -1, 0, 1, 1, -1, 0, 1, -1, -1, 0, 1, 1, -1, 0, 1, -1, -1, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS G. C. Greubel, Table of n, a(n) for n = 0..2500 Index entries for linear recurrences with constant coefficients, signature (0,-1,0,-1,0,-1). FORMULA Euler transform of length 10 sequence [1, -2, 0, 0, 1, 0, 0, 1, 0, -1]. a(n) is multiplicative with a(2) = -1, a(2^e) = 0 if e>1, a(p^e) = 1 if p == 1 (mod 4), a(p^e) = (-1)^e if p == 3 (mod 4) and a(0) = 1. G.f.: 1 + x / (1 + x^2) - x^2 / (1 + x^4). G.f.: (1 + x) * (1 + x^5) / ((1 + x^2) * (1 + x^4)). a(n) = -a(-n) for all n in Z unless n = 0. a(n+8) = a(n) unless n=0 or n=-8. a(4*n) = 0 unless n=0. a(n) = A112299(n) unless n=0. - R. J. Mathar, Apr 19 2015 EXAMPLE G.f. = 1 + x - x^2 - x^3 + x^5 + x^6 - x^7 + x^9 - x^10 - x^11 + x^13 + ... MATHEMATICA a[ n_] := Boole[n == 0] + {1, -1, -1, 0, 1, 1, -1, 0}[[Mod[ n, 8, 1]]]; a[ n_] := If[ n == 0, 1, Sign[ n] SeriesCoefficient[ (1 + x) * (1 + x^5) / ((1 + x^2) * (1 + x^4)), {x, 0, Abs @ n}]]; CoefficientList[Series[(1 + x)*(1 + x^5)/((1 + x^2)*(1 + x^4)), {x, 0, 60}], x] (* G. C. Greubel, Aug 02 2018 *) PROG (PARI) {a(n) = (n==0) + [0, 1, -1, -1, 0, 1, 1, -1][n%8 + 1]}; (PARI) {a(n) = if( n==0, 1, n%2, (-1)^(n\2), n%4 == 2, -(-1)^(n\4), 0)}; (PARI) {a(n) = if( n==0, 1, sign(n) * polcoeff( (1 + x) * (1 + x^5) / ((1 + x^2) * (1 + x^4)) + x * O(x^abs(n)), abs(n)))}; (PARI) x='x+O('x^60); Vec((1 + x)*(1 + x^5)/((1 + x^2)*(1 + x^4))) \\ G. C. Greubel, Aug 02 2018 (MAGMA) m:=60; R:=PowerSeriesRing(Integers(), m); Coefficients(R!((1 + x)*(1 + x^5)/((1 + x^2)*(1 + x^4)))); // G. C. Greubel, Aug 02 2018 CROSSREFS Cf. A112299. Sequence in context: A135839 A071022 A155076 * A176137 A120529 A099443 Adjacent sequences:  A257193 A257194 A257195 * A257197 A257198 A257199 KEYWORD sign,mult,easy AUTHOR Michael Somos, Apr 17 2015 STATUS approved

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Last modified October 15 13:01 EDT 2018. Contains 316236 sequences. (Running on oeis4.)