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A143064 Expansion of a Ramanujan false theta series variation of A089801 in powers of x. +0
2
1, 1, 0, 0, 0, -1, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0 (list; graph; listen)
OFFSET

0,1

REFERENCES

S. Ramanujan, The Lost Notebook and Other Unpublished Papers, Narosa Publishing House, New Delhi, 1988, p. 41

FORMULA

a(n) = b(3n + 1) where b(n) is multiplicative and b(p^(2e)) = (-1)^e if p = 5 (mod 6), b(p^(2e)) = +1 if p = 1 (mod 6) and b(p^(2e-1)) = b(2^e) = b(3^e) = 0 if e>0.

a(4*n + 2) = a(4*n + 3) = a(8*n + 4) = 0.

G.f.: Sum_{k>=0} (-1)^k * x^(3*k^2 + 2*k) * ( 1 + x^(2*k+1) ).

EXAMPLE

q + q^4 - q^16 - q^25 + q^49 + q^64 - q^100 - q^121 + q^169 + q^196 + ...

PROGRAM

(PARI) {a(n) = if( issquare( 3*n + 1, &n), (-1)^(n \ 3) )}

CROSSREFS

Cf. A143062(n) = a(8*n). Convolution of A010054 with A143065.

Sequence in context: A012245 A089801 A089802 this_sequence A163811 A163817 A151667

Adjacent sequences: A143061 A143062 A143063 this_sequence A143065 A143066 A143067

KEYWORD

sign

AUTHOR

Michael Somos, Jul 21 2008

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Last modified December 15 00:47 EST 2009. Contains 170825 sequences.


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