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 A010818 Expansion of Product (1 - x^k)^10 in powers of x. 4
 1, -10, 35, -30, -105, 238, 0, -260, -165, 140, 1054, -770, -595, 0, -715, 2162, 455, 0, -2380, -1820, 2401, -680, 1495, 3080, 1615, -6958, -1925, 0, 0, 5100, -1442, 8330, -5355, 1330, 0, -16790, 0, 8190, 8265, 0, 1918, 0, 8415, -10230, -7140, -9362 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 REFERENCES Newman, Morris; A table of the coefficients of the powers of eta(tau). Nederl. Akad. Wetensch. Proc. Ser. A. 59 = Indag. Math. 18 (1956), 204-216. LINKS Seiichi Manyama, Table of n, a(n) for n = 0..10000 M. Boylan, Exceptional congruences for the coefficients of certain eta-product newforms, J. Number Theory 98 (2003), no. 2, 377-389. S. Cooper, The Quintuple product identity, Int. J. Number Theory 2 (2006), no. 1, 115-161. See after equation (73). S. R. Finch, Powers of Euler's q-Series, arXiv:math/0701251 [math.NT], 2007. FORMULA Expansion of f(-x)^10 in powers of x where f() is a Ramanujan theta function. Expansion of q^(-5/12) * eta(q)^10 in powers of q. - Michael Somos, Jun 09 2011 a(n) = b(12*n + 5) / 48 where b() is multiplicative with b(2^e) = b(3^e) = 0^e, b(p^e) = (1 + (-1)^e) / 2 * p^(2*e) if p == 7 or 11 (mod 12), b(p^e) = b(p) * b(p^(e-1)) - p^4 * b(p^(e-2)) if p == 1 or 5 (mod 12). - Michael Somos, Jun 24 2013 G.f. is a period 1 Fourier series which satisfies f(-1 / (144 t)) = 12^5 (t/i)^5 f(t) where q = exp(2 Pi i t). - Michael Somos, Jan 06 2014 G.f.: Product_{k>0} (1 - x^k)^10. a(49*n + 20) = 2401 * a(n). 48 * a(n) = A234565(3*n + 1). a(7*n + 2) = 0 unless n == 2 (mod 7). - Michael Somos, Jul 18 2014 a(0) = 1, a(n) = -(10/n)*Sum_{k=1..n} A000203(k)*a(n-k) for n > 0. - Seiichi Manyama, Mar 27 2017 G.f.: exp(-10*Sum_{k>=1} x^k/(k*(1 - x^k))). - Ilya Gutkovskiy, Feb 05 2018 EXAMPLE G.f. = 1 - 10*x + 35*x^2 - 30*x^3 - 105*x^4 + 238*x^5 - 260*x^7 - 165*x^8 + ... G.f. = q^5 - 10*q^17 + 35*q^29 - 30*q^41 - 105*q^53 + 238*q^65 - 260*q^89 + ... MATHEMATICA a[ n_] := SeriesCoefficient[ QPochhammer[ x]^10, {x, 0, n}]; (* Michael Somos, Jun 24 2013 *) PROG (PARI) {a(n) = if( n<0, 0, polcoeff( eta(x + x * O(x^n))^10, n))}; /* Michael Somos, Jun 09 2011 */ (PARI) {a(n) = local(m, x, y, z); if( n<0, 0, m = 12*n + 5; z = 0; for( x = -sqrtint(m), sqrtint(m), if( x%6 != 1, next); if( issquare( m - x^2, &y), if( y%6 == 2, y = -y); if( y%6 == 4, z += x*y * (x*x - y*y) ))); z / 6)}; /* Michael Somos, Jun 09 2011 */ (PARI) {a(n) = local(A, p, e, i, x, y, a0, a1); if( n<0, 0, n = 12*n + 5; A = factor(n); 1 / 48 * prod( k=1, matsize(A)[1], if( p=A[k, 1], e=A[k, 2]; if( p<5, 0, if( p%12 > 6, if( e%2, 0, p^(2*e)), forstep( i = 1, sqrtint( p), 2, if( issquare( p - i^2, &y), x=i; break)); if( p%12 == 5, a1 = 8 * x*y * (x-y) * (x+y) * (-1)^((x%6==1) + (y%6==4)), a1 = 2 * (x^2-y^2+2*x*y) * (x^2-y^2-2*x*y) * (-1)^(x%6==3) ); a0 = 1; y = a1; for( i=2, e, x = y * a1 - p^4 * a0; a0=a1; a1=x); a1 )))))}; /* Michael Somos, Jun 24 2013 */ CROSSREFS Cf. A122266, A234565. Sequence in context: A230895 A254674 A260336 * A243939 A065195 A115149 Adjacent sequences:  A010815 A010816 A010817 * A010819 A010820 A010821 KEYWORD sign AUTHOR STATUS approved

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Last modified June 21 23:16 EDT 2018. Contains 305646 sequences. (Running on oeis4.)