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

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A007706 1 + coefficient of x^n in Product (1-x^k ), k=1.. inf (essentially the expansion of the Dedekind function eta(x)).
(Formerly M0013)
3
2, 0, 0, 1, 1, 2, 1, 2, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1 (list; graph; refs; listen; history; internal format)
OFFSET

0,1

REFERENCES

M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, Tenth Printing, 1972, p. 825.

B. Schoeneberg, Elliptic Modular Functions, Springer-Verlag, NY, 1974, p. 70.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

T. D. Noe, Table of n, a(n) for n=0..1000

M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].

M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, Tenth Printing, 1972, p. 825.

FORMULA

eta(z) = q^(1/24) Product( 1-q^m, m=1..inf), q=exp(2 Pi i z).

G.f.: 1/(1-x)+Prod_{k>0}(1-x^k). - Michael Somos Jun 26 2004

MAPLE

eta := q^(1/24)*mul( (1-q^m), m=1..100);

MATHEMATICA

p[n_] := p[n] = Expand[p[n-1]*(1-x^n)]; p[1] = 1-x; a[n_] := 1+Coefficient[p[n], x^n]; a[0] = 2; Table[a[n], {n, 0, 104}](* From Jean-François Alcover, Jan 06 2012 *)

PROG

(PARI) a(n)=if(n<0, 0, 1+polcoeff(eta(x+x*O(x^n)), n)) /* Michael Somos Jun 26 2004 */

CROSSREFS

Cf. A010815.

Sequence in context: A039977 A197548 A029403 * A035144 A157045 A035208

Adjacent sequences:  A007703 A007704 A007705 * A007707 A007708 A007709

KEYWORD

nonn,easy,nice

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

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 17 23:40 EST 2012. Contains 206085 sequences.