login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A128808 Coefficients of the invariant of degree 20 associated with the icosahedral group. 1
-1, 228, -494, -228, -1 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

REFERENCES

A. Erdelyi, Higher Transcendental Functions, McGraw-Hill, 1955, Vol. 3, p. 11.

F. Klein, Lectures on the Icosahedron ..., 2nd Rev. Ed., 1913; reprinted by Dover, NY, 1956; see p. 61.

S. Mukai, An Introduction to Invariants and Moduli, Cambridge, 2003; see p. 19.

LINKS

Table of n, a(n) for n=0..4.

EXAMPLE

H = -(x^20 + y^20) + 228*(x^15*y^5 - x^5*y^15) - 494*x^10*y^10.

CROSSREFS

Cf. A128809. The third invariant (which does not have its own entry) is f = x*y*(x^10 + 11*x^5*y^5 - y^10).

Sequence in context: A252228 A252221 A154519 * A043411 A172531 A258557

Adjacent sequences:  A128805 A128806 A128807 * A128809 A128810 A128811

KEYWORD

sign,fini,full

AUTHOR

N. J. A. Sloane, Apr 10 2007

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 3 08:07 EST 2021. Contains 349445 sequences. (Running on oeis4.)