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A002511 Expansion of a modular function for Gamma_0(21).
(Formerly M1566 N0610)
+0
1
1, 1, 2, 6, 8, 13, 29, 44, 66, 122, 184, 269, 448, 668, 972, 1505, 2205, 3153, 4677, 6717, 9480, 13656, 19245, 26793, 37714, 52301, 71894, 99392, 135969, 184637, 251492, 339793, 456432, 613837, 820388, 1091154, 1451243, 1920637, 2531468 (list; graph; listen)
OFFSET

6,3

REFERENCES

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

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

Newman, Morris; Construction and application of a class of modular functions. II. Proc. London Math. Soc. (3) 9 1959 373-387.

FORMULA

eta(21z)^9/(eta(z)*eta(3z)^3*eta(7z)^5)

Euler transform of period 21 sequence [1, 1, 4, 1, 1, 4, 6, 1, 4, 1, 1, 4, 1, 6, 4, 1, 1, 4, 1, 1, 0, ...]. - Michael Somos Nov 10 2005

PROGRAM

(PARI) {a(n)=local(A); if(n<6, 0, n-=6; A=x*O(x^n); polcoeff( eta(x^21+A)^9/ eta(x+A)/eta(x^3+A)^3/eta(x^7+A)^5, n))} /* Michael Somos Nov 10 2005 */

CROSSREFS

Sequence in context: A054248 A038108 A087327 this_sequence A074383 A107505 A074400

Adjacent sequences: A002508 A002509 A002510 this_sequence A002512 A002513 A002514

KEYWORD

nonn,easy

AUTHOR

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

EXTENSIONS

More terms from Kok Seng Chua (chuaks(AT)ihpc.nus.edu.sg), Jan 14 2001

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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