OFFSET
1,1
EXAMPLE
From the primes, construct the series 1+2x+3x^2+5x^3+7x^4+... a(1) is always the coefficient of x, here 2. Divide by (1+2x) to get the quotient (1+a(2)x^2+...), which here gives a(2)=3. Then divide this quotient by (1+a(2)x^2), i.e. here (1+3x^2), to get (1+a(3)x^3+...), giving a(3)=-1.
MATHEMATICA
ser=1+Sum[Prime[i]x^i, {i, 110}]; ss=1+2x; Do[ser=Normal[Series[ser/(Take[ser, 2]), {x, 0, 105}]]; ss+=ser[[2]], {100}]; A147557=CoefficientList[ss, x] [From Zak Seidov, Nov 10 2008]
CROSSREFS
KEYWORD
sign
AUTHOR
Neil Fernandez, Nov 07 2008
EXTENSIONS
Corrected and extended by Zak Seidov, Nov 10 2008
STATUS
approved