cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A198243 G.f.: q-Sinh(x) evaluated at q=-x.

Original entry on oeis.org

1, 0, 0, 0, 0, -1, -2, -2, -1, 0, 0, -1, -2, -2, 0, 4, 7, 6, 3, 2, 3, 4, 5, 6, 6, 6, 8, 10, 6, -6, -18, -20, -13, -7, -8, -13, -16, -15, -13, -15, -25, -41, -53, -53, -44, -32, -16, 5, 22, 25, 18, 13, 14, 19, 29, 41, 44, 38, 43, 72, 109, 130, 135, 146, 180, 232, 274
Offset: 1

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Author

Paul D. Hanna, Aug 07 2012

Keywords

Comments

Note: q-Sinh(x) = Sum_{n>=0} x^(2*n+1) * q^(n*(2*n+1)) / Product_{k=1..2*n+1} (1-q^k)/(1-q).

Examples

			G.f.: x - x^6 - 2*x^7 - 2*x^8 - x^9 - x^12 - 2*x^13 - 2*x^14 + 4*x^16 + 7*x^17 +...
		

Crossrefs

Cf. A152398 (e_q), A198197 (E_q), A198242 (q-Cosh), A198201 (q-cosh), A198202 (q-sinh).

Programs

  • PARI
    {a(n)=local(Sinh_q=sum(k=0, sqrtint(n+4), (-x)^(k*(2*k+1))*x^(2*k+1)/(prod(j=1, 2*k+1, (1-(-x)^j)/(1+x))+x*O(x^n)))); polcoeff(Sinh_q, n)}
    for(n=0,81,print1(a(n),", "))

Formula

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