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 A204059 a(n) = Pell(n) * sum{d|n} (-1)^(n/d) / Pell(d), where Pell(n) = A000129(n). 1
 1, -1, 6, -17, 30, -48, 170, -645, 1183, -1270, 5742, -22604, 33462, -40868, 240756, -746637, 1136690, -1884529, 6625110, -23217030, 46565244, -46627416, 225058682, -975425316, 1356970471, -1583502622, 9182205852, -26257649200, 44560482150, -77433044928 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS FORMULA G.f.: Sum_{n>=1} x^n/(1 + A002203(n)*x^n + (-1)^n*x^(2*n)) where A002203 is the companion Pell numbers. a(2*n-1) = A203797(2*n-1). EXAMPLE G.f.: A(x) = x - x^2 + 6*x^3 - 17*x^4 + 30*x^5 - 48*x^6 + 170*x^7 +... where A(x) = x/(1+2*x-x^2) + x^2/(1+6*x^2+x^4) + x^3/(1+14*x^3-x^6) + x^4/(1+34*x^4+x^8) + x^5/(1+82*x^5-x^10) + x^6/(1+198*x^6+x^12) +...+ x^n/(1 + A002203(n)*x^n + (-1)^n*x^(2*n)) +... PROG (PARI) {Pell(n)=polcoeff(x/(1-2*x-x^2+x*O(x^n)), n)} {a(n)=Pell(n) * sumdiv(n, d, -(-1)^(n/d)/Pell(d))} (PARI) /* G.f. using companion Pell numbers: */ {A002203(n)=polcoeff(2*(1-x)/(1-2*x-x^2+x*O(x^n)), n)} {a(n)=polcoeff(sum(m=1, n, x^m/(1 + A002203(m)*x^m + (-1)^m*x^(2*m) +x*O(x^n))), n)} CROSSREFS Cf. A203797, A111075, A203802, A000129, A002203. Sequence in context: A061875 A063230 A212461 * A067559 A096426 A130051 Adjacent sequences:  A204056 A204057 A204058 * A204060 A204061 A204062 KEYWORD sign AUTHOR Paul D. Hanna, Jan 13 2012 STATUS approved

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Last modified September 29 06:29 EDT 2020. Contains 337425 sequences. (Running on oeis4.)