OFFSET
1,3
FORMULA
q(x)=x^10 + x^9 - x^7 - x^6 - x^5 - x^4 - x^3 + x + 1; p(x)=x^10*q(x+1/x); p(x)=1 + x + 10 x^2 + 8 x^3 + 44 x^4 + 28 x^5 + 113 x^6 + 57 x^7 + 191 x^8 + 79 x^9 + 227 x^10 + 79 x^11 + 191 x^12 + 57 x^13 + 113 x^14 + 28 x^15 + 44 x^16 + 8 x^17 + 10 x^18 + x^19 + x^20; a(n)=Coefficient_Expansion(x^20*p(1/x)).
MATHEMATICA
f[x_] = x^10 + x^9 - x^7 - x^6 - x^5 - x^4 - x^3 + x + 1; h[x_] = ExpandAll[x^10*f[x + 1/x]]; g[x] = ExpandAll[x^20*h[1/x]]; a = Table[SeriesCoefficient[ Series[1/g[x], {x, 0, 30}], n], {n, 0, 30}]
CROSSREFS
KEYWORD
uned,sign
AUTHOR
Roger L. Bagula and Gary W. Adamson, Oct 24 2008
STATUS
approved