OFFSET
0,11
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..1000
FORMULA
Euler transform of period 4 sequence [1, 0, -1, 0, ...]. - Michael Somos, Nov 10 2005
G.f.: Product_{k>0} (1-x^(2k-1))^((-1)^k). - Michael Somos, Nov 11 2005
G.f.: exp( Sum_{k >= 1} 1/(k*(x^k + x^(-k))) ). - Peter Bala, Sep 28 2023
MAPLE
# Uses EulerTransform from A358369.
a := EulerTransform(BinaryRecurrenceSequence(0, -1)):
seq(a(n), n=0..86); # Peter Luschny, Nov 17 2022
PROG
(PARI) {a(n)=if(n<0, 0, polcoeff( prod(k=0, n\2, (1-x^(2*k+1))^(-(-1)^k), 1+x*O(x^n)), n))} /* Michael Somos, Nov 11 2005 */
(Sage) # uses[EulerTransform from A166861]
b = BinaryRecurrenceSequence(0, -1)
a = EulerTransform(b)
print([a(n) for n in range(87)]) # Peter Luschny, Nov 17 2022
CROSSREFS
KEYWORD
sign,look
AUTHOR
N. J. A. Sloane, Nov 09 2005
STATUS
approved