login
This site is supported by donations to The OEIS Foundation.
Logo

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A118272 Expansion of q^(-2/3)(eta(q)eta(q^3)eta(q^6)/eta(q^2))^2 in powers of q. 1
1, -2, 1, -4, 8, -6, 6, -8, 14, -10, 1, -16, 20, -14, 12, -16, 31, -18, 8, -20, 32, -28, 18, -24, 38, -32, 6, -28, 44, -30, 24, -40, 57, -34, 14, -36, 72, -38, 30, -48, 62, -52, 1, -44, 68, -46, 48, -56, 74, -50, 20, -64, 80, -64, 42, -56, 108, -58, 12, -60, 112, -76, 48, -64, 98, -66, 31, -80, 104, -80, 54, -88 (list; graph; refs; listen; history; internal format)
OFFSET

0,2

FORMULA

Euler transform of period 6 sequence [ -2, 0, -4, 0, -2, -4, ...].

A118271(3n+2)=-3a(n).

PROG

(PARI) {a(n)=local(A); if(n<0, 0, A=x*O(x^n); polcoeff( (eta(x+A)*eta(x^3+A)*eta(x^6+A)/eta(x^2+A))^2, n))}

CROSSREFS

Sequence in context: A059146 A059148 A158451 * A112173 A058543 A156817

Adjacent sequences:  A118269 A118270 A118271 * A118273 A118274 A118275

KEYWORD

sign

AUTHOR

Michael Somos, Apr 21 2006

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
Recent Additions | More pages | Superseeker | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified February 15 23:53 EST 2012. Contains 205860 sequences.