A109546 - OEIS

A109546

(4^(n+1)-(-1)^n 9 )/5.

5, 11, 53, 203, 821, 3275, 13109, 52427, 209717, 838859, 3355445, 13421771, 53687093, 214748363, 858993461, 3435973835, 13743895349, 54975581387, 219902325557, 879609302219, 3518437208885, 14073748835531, 56294995342133

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OFFSET

1,1

COMMENTS

a(n)= 2^n th coefficient of - eta(z)^5 eta (3z) eta (6z)^4/ eta(2z)^4.

LINKS

Table of n, a(n) for n=1..23.

FORMULA

a(0)=-1, a(n)=4*a(n-1)-(-1)^n * 9, n >=1.

EXAMPLE

a(3)=53, since (4^4+9)/5=53

PROG

(PARI) for (n=1, 100, print( (4^(n+1)-(-1)^n *9 )/5));

CROSSREFS

Sequence in context: A228865 A149527 A201180 * A104065 A212304 A018545

Adjacent sequences: A109543 A109544 A109545 * A109547 A109548 A109549

KEYWORD

nonn

AUTHOR

Kok Seng Chua (chuaks(AT)ihpc.a-star.edu.sg), Aug 30 2005

STATUS

approved